Investigation of a cross-border measles outbreak in Moroto District, northeastern Uganda, March–September, 2024

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We investigated to assess magnitude of the outbreak, identify its source and risk factors, and recommend evidence-based control and prevention measures. Methods We defined a suspected case as onset of fever and maculopapular rash, and ≥ 1 of cough, coryza, or conjunctivitis in a resident of Moroto District from March 15 to September 22, 2024. A confirmed case was a suspected case with a positive measles-specific IgM test. We identified cases using health facility records and active case search within the health facilities. We conducted a hospital-based case-control study with a 1:2 ratio. Controls were children admitted to the pediatric ward with an alternative diagnosis but no history of fever, rash, or conjunctivitis. We used logistic regression to identify risk factors. We estimated the vaccine effectiveness (VE) from adjusted odds ratio (aOR) associated with vaccination (VE = 1-aOR) % and vaccination coverage (VC) from percentage of vaccinated controls. Results We identified 290 case-patients (275 suspected and 15 confirmed), with 6 deaths (case fatality rate [CFR] = 2%). The index case-patient was a 10-month-old child who had returned from the Western Turkana Region of Kenya, where a measles outbreak was ongoing. The overall attack rate (AR) was 19/10,000. Lotisan Sub-county (AR = 50/10,000) and children < 1 year (AR = 194/10,000) were the most affected. Being vaccinated was protective (aOR = 0.11, 95%CI = 0.03–0.4). Visiting a health facility 7–21 days before the onset of rash (aOR = 3.8, 95%CI = 1.3–11) and having malnutrition (aOR = 6.1, 95%CI = 1.3–27) increased the odds of contracting measles. Estimated VC was 67% and VE was 89% (95%CI = 60–97%). Conclusion The outbreak was likely imported from Kenya, and was propagated by low vaccination coverage, and healthcare visits within the exposure period. To prevent similar future outbreaks, it is crucial to improve vaccination coverage, strengthen triage systems at health facilities for prompt case identification and management, and enhance cross-border surveillance. Measles Disease outbreak Cross-border health surveillance Vaccine-effectiveness Vaccine-coverage Uganda Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Measles is a highly contagious, vaccine-preventable viral disease primarily affecting children < 5 years, with a case fatality rate (CFR) of 5–10% [ 1 , 2 ]. The incubation period of measles is 7–21 days [ 3 ]. The disease presents with fever, maculopapular rash, cough, and conjunctivitis. Severe complications such as pneumonia, diarrhea, and encephalitis are more likely in malnourished children, those with advanced HIV, and those living in overcrowded conditions [ 1 ]. Measles remains one of the leading causes of morbidity and mortality worldwide with 103 countries reporting outbreaks and an increase in measles related deaths from 95,000 in 2021 to 136,200 in 2023 [ 4 ]. This resurgence was a result of a decline in vaccination coverage worldwide. The decline in vaccination coverage was exacerbated by the emergence of the COVID-9 pandemic that ravaged the health systems globally. Globally the first dose of Measles Containing Vaccine (MCV) coverage declined from 86% in 2019 to 81% in 2021 [ 3 , 4 ]. The World Health Organization (WHO) recommends two doses of MCV with the first dose administered between 9 and 12 months of age and the second dose administered at the age of 15–18 months of age, the second dose should be at least one month apart from the first one [ 1 ]. In Uganda, the first dose of measles (MCV1) coverage was 85% in 2022, while the second dose (MCV2), introduced in 2022, remains suboptimal at 44% [ 5 , 6 ]. To achieve herd immunity and prevent outbreaks, coverage should exceed 93% at the district level. Due to low MCV coverage, in 2024 alone, by mid-year, Uganda had experienced 20 measles outbreaks across various districts [ 6 , 7 ]. On June 26, 2024, the Uganda Ministry of Health (MoH) through the National Public Health Emergency Operations Centre received notification of a measles outbreak in Moroto District, Karamoja Region. Out of thirteen blood samples that were sent to the Uganda Virus Research Institute (UVRI), seven of them tested positive for measles-specific Immunoglobulin M (IgM) antibodies. We investigated the measles outbreak to determine its scope, assess risk factors for transmission, identify the source, and evaluate vaccine effectiveness and coverage, so as to recommend evidence-based control measures and strategies for future prevention. Methods Outbreak area We conducted the investigation in Moroto District in Karamoja Region, northeastern Uganda. This region is inhabited by the Karamojong who are predominantly nomadic pastoralists. The district neighbours the Turkana Region of Kenya which is also occupied by nomadic pastoralists known as the Turkana people. Both people have intertwined cultures with a lot in common. In 2024, the estimated population of Moroto District was 128,800, with a low population density of less than 50 people per km² [ 12 , 13 ]. The district is divided into six sub-counties, one town council, and a municipality with two divisions. Moroto District has 18 health facilities, 17 of which provide immunization services. These include one regional referral hospital, six Health Centers III (HC IIIs), and 11 Health Centers II (HC IIs). St. Pius Kidepo HC III is the only private non-for-profit (PNFP) facility, while the rest are public health facilities. All but one health facility offers immunization services, with both static and outreach services available. Case definition and case finding We defined a suspected case as onset of fever and maculopapular rash and one or more of the following symptoms: cough, runny nose or conjunctivitis in a resident of Moroto District from March 15, 2024 to September 24, 2024. A confirmed case was a suspected case with positive results for IgM measles-specific antibody test in a resident of Moroto District. We line-listed suspected measles cases by reviewing health facility records at Moroto Regional Referral Hospital (RRH) and St. Pius, Kidepo HC III because the rest of the health facilities were inaccessible due to insecurity that was ongoing in the area [ 10 , 11 ]. Line-listing involved compiling detailed information on each suspected case, including demographic and clinical data. Additional cases were identified through collaboration with Health Facility Surveillance Focal Persons (HFSFPs), who reviewed records at facilities that we were unable to reach due to security challenges and subsequently provided the line-lists. The HFSFP shared the updated line-lists via email on a daily basis. Data on demographics, clinical characteristics, vaccination status, exposure history, treatment and admission history were collected using standard case investigation forms ( Supplementary material: Appendix 1 ). Laboratory investigations Samples of whole blood were collected from 21 suspected case-patients and sent to Uganda Virus Research Institute (UVRI) for Measles specific IgM testing. Descriptive epidemiology We constructed an epidemic curve to assess the temporal distribution of measles cases. We computed attack rates (ARs) by person, and place using based on the 2024 projected populations from the Uganda National Bureau of Statistics (UBOS) 2014 census as the denominator and presented the results using tables. Distribution of cases by place was further illustrated on maps using Quantum Geographic Information System (QGIS). Environmental assessment We made an observational assessment of the pediatric outpatient department, inpatient ward and the designated isolation ward to understand the flow of the patients and observe for possible risk factors for nosocomial spread. We assessed the outpatient and the in-patient registers to assess reasons for attendance and admission. Additionally, we also screened the patients for symptoms of measles. Hypothesis generation We conducted 30 hypothesis generating interviews from suspected case-patients using the measles case investigation form. The interviews were among the initial case-patients that we were able to reach at the start of our investigation. The hypothesis-generating interviews were conducted to identify possible risk factors and inform further investigation into the source and spread of the outbreak. Caretakers were asked about potential exposures in the three weeks prior to the onset of symptoms, including visits to health facilities, lack of vaccination, hosting visitors from Kenya or neighboring districts, and travel outside the district. Child health cards were used as the primary source of vaccination information; when unavailable, caretaker recall was relied upon, which was further validated by asking for vaccination site and age at vaccination. Interviews were also conducted with the District Health Team (DHT) to explore potential exposure factors and identify the source of the outbreak. Case-control study We conducted a matched case-control study to evaluate our hypotheses. We recruited 83 case patients who had been line listed by the time of the case-control study. For each case, two controls were selected, aged 6 months to 5 years, with no history of fever, rash, or conjunctivitis between March 15 and July 23, 2024. Controls had an alternative diagnosis confirmed by either a pediatrician or a medical officer and were residents of Moroto District. They were selected consecutively from the pediatric inpatient and outpatient wards upon exiting the consultation room. Data were collected using KoboToolTM, with analysis conducted using Epi Info 7.1.5 (CDC, Atlanta, USA). To assess the risk factors for measles infection, adjusted odds ratios (aOR) and their corresponding 95% confidence intervals (CIs) were calculated. Factors found to be statistically significant (p value < 0.05) in bivariate analysis were included in the multivariable logistic regression analysis. Vaccine coverage We estimated the vaccine coverage (VC) using the percentage of controls with a history of measles vaccination in the case control study, under the assumption that the controls were representative of the general population. For MCV-1, the VC was determined by dividing the number of eligible controls who were vaccinated by the total number of eligible controls. For overall VC, the calculation was based on the total number of controls, with the numerator being the number of controls who had received the vaccination. Additionally, we extracted data from the national health information database software, DHIS2 for the vaccination coverage that was reported for the district Vaccine Effectiveness Vaccine effectiveness (VE) was estimated among the case-control participants to assess the vaccine’s effectiveness in preventing measles during the outbreak. We calculated VE using the formula: VE = 1- aOR Where aOR is the odds ratio associated with having been vaccinated with at least one dose of measles vaccine, adjusted for risk factors that were significant during the univariate analysis, using logistic regression. Results Descriptive epidemiology We identified 290 case-patients (275 suspected cases, 15 confirmed cases. During this outbreak 6 deaths were recorded. The index case-patient, was a 10-month-old child from Kosiroi Village in Tapac Sub-county, located near the Kenyan border in the Western Turkana Region. This child had received one dose of the measles-containing vaccine (MCV) and had returned from Kenya on April 1, 2024, where a measles outbreak was ongoing, just four days before symptoms began. This region had an ongoing measles outbreak. The child visited Moroto RRH on April 5, 2024 and came into contact with other children, after which more cases were reported from other sub-counties. The second case-patient was a two-year-old female from Lotisan sub-county who had initially visited the health facility on the same day as the index case-patient. The third case-patient was from the neighborhood of the second case-patient in Lotisan sub-county. From this point onwards, the epidemic curve showed a propagated pattern with multiple peaks over the outbreak period (Fig. 1). There was delay in receiving laboratory results of measles IgM, which took two months to be made available to the district. On June 23, 2024, a separate isolation unit was designated at the hospital for the measles cases. Six deaths were recorded, all occurring at Moroto RRH (MRRH). The deceased died from complications of severe pneumonia, with underlying malnutrition. Three of the deaths were among children unvaccinated against measles, and three had an unknown vaccination status. Figure 1: Distribution of measles cases by the date of onset of symptoms, Moroto District, Uganda, March–September, 2024 (n = 290) All cases presented with fever and generalized rash. The majority of the cases had running nose (71%), and red eyes (67%) (Fig. 2 ). Other symptoms were cough, diarrhea, generalized body weakness, poor feeding. 22% (52/236) of the cases had complications. The common complications during this outbreak were diarrhea (16%), diarrhea and pneumonia (3%), and pneumonia alone (2.5%). The most affected age group was < 1 year of age (194/10,000) followed by the 1–4 years age group (47/10, 0000), and 5–15 years (2/10,000). The AR was similar among males (20/10,000) and females (18/10,000) (Table 1 ). Table 1 Measles AR by age group during a measles outbreak, Moroto District, Uganda, March–September 2024 Category Frequency Population AR/10,000 Age group < 1 year 103 5,306 194 1–4 years 118 25,297 47 5–15 years 15 64,168 2 Sex Female 106 59,200 18 Male 130 64,600 20 The most affected sub-counties were Lotisan (50/10,000) and Rupa (41/10,000). These were followed by Nandunget (17/10,000), Northern Division (14/10,000), Loputuk (13/10,000), Katikekile (9/10,000), Southern Division (7/10,000), and Tapac (1/10,000) sub-counties. The overall AR was 19/10,000 (Fig. 3 ). Environmental findings Prior to the confirmation of the outbreak, measles case-patients were being treated alongside other patients in the same wards. After the confirmation of the outbreak by the district, an isolation ward was designated at Moroto RRH and then much later as a result of increase in cases at St. Pius Kidepo HC III. There was free mixing of suspected measles case-patients and non-measles patients in the pediatric out patients. Hypothesis generation findings Of the 30 cases-patients, 25 (83%) were not vaccinated, 19 (63%) had visited a health facility, 8 (27%) were malnourished, and 2 (7%) had received a visitor from a neighboring district. Interviews with the district health officer, and district surveillance focal person (DSFP) revealed that there was frequent movement across the Ugandan border with Kenya and they had been on high alert since the beginning of the year following information from the Kenyan public health officials about a measles outbreak that was ongoing in the Western Turkana Region. We hypothesized that the spread of the outbreak was facilitated by factors including sub-optimal vaccination coverage, travel to a neighboring country, malnutrition, and prior visits to health facilities before the onset of symptoms. Case-control study findings, vaccine coverage and vaccine effectiveness At multivariable analysis, lack of vaccination against measles (aOR = 8.9, 95%CI = 2.5–32), malnutrition (aOR = 6.1, 95%CI = 1.3–27), and visiting a health facility during exposure period (aOR = 3.8, 95%CI = 1.3–11) were significantly associated with measles transmission (Table 2 ). Table 2 Factors associated with measles transmission during the outbreak in Moroto District, Uganda, March–September 2024 Risk factor Cases n (%) Controls n (%) Crude OR (95% CI) aOR (95%CI) Lack of Vaccination Yes 22 (50) 11 (9) 10 (4.2–23) 8.9 (2.5–32) No 22 (50) 111 (9) Ref Ref Malnutrition Yes 24 (29) 24 (15) 2.4 (1.3–4.6) 6.1 (1.3–27) No 59 (71) 142 (85) Ref Ref *Visiting a health facility during exposure period Yes 37 (45) 14 (18) 3.6 (1.7–7.7) 3.8 (1.3–11) No 46 (55) 63 (82) Ref Ref Visitor from another district Yes 11 (13) 9 (5) 2.7 (1.1–6.8) 3.9 (0.3–53) No 72 (87) 157 (95) Ref Ref Vitamin A in the last 6 months Yes 69 (83) 153 (92) 0.42 (0.19–0.95) 0.5 (0.1–3.0) No 14 (17) 13 (8) Ref Ref *Exposure period was defined as 21 days prior to onset of rash; Ref: Reference category; OR: Odds ratio; aOR: Adjusted odds ratio; CI: Confidence interval Table 3 Estimation of vaccine coverage and effectiveness during measles outbreak in Moroto District, Uganda, March–September 2024 Risk factor Cases n (%) Controls n (%) Crude OR (95% CI) aOR (95%CI) Vaccination Yes 22 (50) 111 (91) 0.099 (0.04–0.26) 0.11 (0.03–0.4) No 22 (50) 11 (9) Ref Ref Ref: Reference category; OR: Odds ratio; aOR: Adjusted odds ratio; CI: Confidence interval The estimated VE was 89% (95% CI = 60–97). The estimated VC, based on the percent of controls that had a history of being vaccinated against measles, was 91% among those ≥ 9 months of age and 67% for all the controls regardless of eligibility. The VC from DHIS2 showed the overall VC for the district was 77% for MCV1 and 15% for MCV2. It varied for the different sub-counties with Rupa with the lowest MCV1 coverage of 29% and Southern Division with the lowest MCV2 coverage of 4% (Fig. 4 ). Discussion Our investigation revealed that the measles outbreak was likely introduced from the neighboring Turkana Region in Western Kenya, which had been experiencing a large outbreak. Vaccination provided strong protection against the disease, while visits to healthcare facilities during exposure period and malnutrition were associated with an increased risk of measles infection. The estimated vaccine coverage was 67% and vaccine effectiveness of 89%. Rupa Sub-county, with the lowest vaccine coverage had the highest attack rate. Overall, these findings emphasize the need for enhanced vaccination efforts. This measles outbreak was likely introduced through cross-border transmission from the Western Turkana Region, which had been experiencing a measles outbreak since December 2023 [ 13 ]. Both regions are home to nomadic pastoralist communities that frequently cross the border for cultural and grazing activities, a phenomenon that has previously been implicated in the spread of vaccine-preventable diseases [ 14 ]. Evidence from other regions, such as Somalia and Chad, suggests that integrating animal vaccination programs with human vaccination initiatives could improve coverage within such nomadic populations [ 20 , 21 ]. To prevent future outbreaks, enhancing cross-border information sharing at both the district and regional levels, along with strengthening surveillance at border points, is critical to mitigate the risks posed by cross-border movements [ 17 ]. The outbreak was further facilitated by the mixing of measles and non-measles patients before the outbreak was confirmed and an isolation unit established at Moroto RRH. Nosocomial transmission has been a known factor in measles outbreaks [ 8 , 16 , 17 ]. The highly contagious nature of measles, along with its infectious period before the onset of classic symptoms like rash and fever, makes implementing screening and isolation protocols particularly challenging. The WHO recommends that vaccination should also be offered to all exposed, non-immune children within 72 hours of exposure for effective protection [ 21 ]. Strengthening screening protocols at healthcare facilities, combined with the timely isolation of suspected measles cases, could minimize nosocomial transmission in future outbreaks. Malnutrition, which is highly prevalent in this outbreak area was associated with increased odds of measles infection. Studies in Afar District of north eastern Ethiopia and Yemen found similar findings with malnutrition increasing the odds of measles disease [ 19 , 20 ]. This area had been experiencing an increase in acute food insecurity and malnutrition levels during the period of the outbreak [ 24 ]. Malnutrition also heightens the risk of mortality in children with measles; in this study, all five recorded deaths had malnutrition as an underlying condition. These findings align with other studies conducted in the Horn of Africa and beyond [ 22 , 23 ]. To mitigate the impact of future similar outbreaks, and reduce measles-associated mortality in vulnerable communities, district authorities should consider addressing food insecurity and malnutrition as part of the broader public health response. Vaccination was protective against measles disease. Measles vaccination is globally recognized as the primary strategy for preventing outbreaks and ultimately achieving disease elimination. The WHO recommends two doses of MCV with the first dose administered at 9 months and the second dose at 15–18 months of age, and a VC of at least 80% for MCV2 [ 1 ]. However, our findings revealed a high attack rate among children1 year, suggesting the need for policy revision to target children as young as 6 months for the first MCV dose. A global review of measles cases between 2013 and 2017 indicated that 13% of all measles cases in Sub-Saharan Africa occurred among children who were not eligible for MCV, recommending a country-level data analysis and potential revision of immunization strategies to lower the age for the first MCV dose [ 24 , 25 ]. However, there are concerns on the immunogenicity of MCV administered at < 9 months and WHO recommends MCV at 6 months only during high risk period. Children who get MCV at 6 months during the high risk period are recommended to follow the normal schedule for the subsequent MCV doses [ 1 ]. Some studies have demonstrated good immunogenicity when MCV was administered at < 9 months with subsequent protective effect against measles outbreaks [ 29 , 30 ]. Maternal antibodies have also been found to wane much earlier and unable to provide protection to infants beyond the 6 months of age [ 31 ]. To prevent and control future outbreaks, it is essential to strengthen and support routine vaccination programs, and consider revising the national immunization schedule to administer the first MCV dose at 6 months of age. Our investigation found an estimated VE of 89%. This was higher than in a previous study that found a VE 85%, but lower than in another study in Uganda that found a VE of 95% [ 29 , 18 ]. However, the VE was within the range of findings of systematic review of measles that found a median VE of 77%, with an (interquartile range [IQR] of 62–91) % when MCV1 was administered at 9–11 months. Administration of MCV1 at ≥ 12 months resulted in higher VE (median of 92%, IQR [86–96%]). VE findings from the field vary and depend on the number of doses administered, vaccine handling and storage, cold chain failure and host factors such as malnutrition and HIV infection [ 33 ]. We recommend strengthening of the vaccination program in the district with emphasis on MCV2 to further improve the VE. Study limitations The outbreak investigation had some limitations. There was ongoing insecurity in the most affected communities of Lotisan and Rupa Sub-counties of the district during this outbreak [ 12 ]. We could not access the affected communities, this could have led to underestimation of the magnitude of the outbreak and also interviewing more severe case-patients who were more likely to seek care. We enrolled hospital controls which was also as a result of the insecurity that was ongoing and there is a possibility that this could have introduced a misclassification bias. The bias was minimized by cautious selection of the controls and only considering those without symptoms of measles and with a diagnosis other than measles made by either a pediatrician or a medical officer at the hospital. Conclusion This measles outbreak was likely introduced from the Western Turkana Region of Kenya to Moroto District, Karamoja Region, through cross-border movement. The outbreak was propagated by the mixing of case-patients with other children seeking care at various health facilities, facilitating nosocomial transmission. Additionally, malnutrition and low measles vaccination coverage in the area contributed to the spread of the outbreak. To mitigate the risk of future outbreaks, it is essential to improve vaccination coverage, strengthen triage systems at health facilities for early case detection and management, and improve cross-border surveillance. Additionally, it is essential to address malnutrition and food insecurity in regions vulnerable to measles outbreaks for better public health outcomes. Abbreviations aOR Adjusted Odds Ratio AR Attack Rate CDC Centers for Disease Control and Prevention CFR Case Fatality Rate DHIS2 District Health Information System 2 DHT District Health Team EOC Emergency Operations Centre HFSFP Health Facility Surveillance Focal Person HC II Health Center II HC III Health Center III IgM Immunoglobulin M MCV Measles Containing Vaccine MCV1 First dose of Measles Containing Vaccine MCV2 Second dose of Measles Containing Vaccine MoH Ministry of Health RRH Regional Referral Hospital UVRI Uganda Virus Research Institute VE Vaccine Effectiveness VC Vaccine Coverage WHO World Health Organization Declarations Ethics approval and consent to participate This outbreak investigation was in response to a public health emergency and was therefore determined to be non-research. The Ministry of Health (MoH) gave permission to investigate this outbreak. In agreement with the International Guidelines for Ethical Review of Epidemiological Studies by the Council for International Organizations of Medical Sciences (1991) and the Office of the Associate Director for Science, US CDC/Uganda, it was determined that this activity was not human subject research and that its primary intent was public health practice or disease control activity (specifically, epidemic or endemic disease control activity). This activity was reviewed by the US CDC and was conducted consistent with applicable federal law and CDC policy. §§See, e.g., 45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq. All experimental protocols were approved by the US CDC human subjects review board (The National Institute for Occupational Safety and Health Institutional Review Board) and the Uganda Ministry of Health and were performed in accordance with the Declaration of Helsinki. We sought permission to conduct the investigation from the District health authorities of Moroto District. We obtained verbal consent from the respondents’ parents/caretakers on behalf of their children. We informed the participants that their participation was voluntary and their refusal to participate would not have any negative consequences to them. Before sharing and analyzing the data collaboratively among members of the investigation team, we deleted all identifiable information (i.e., name, address, phone number, etc.). Acknowledgements We acknowledge the support of the Moroto District local government and Karamoja Regional Emergency Operations Centre (EOC) who worked with us during this outbreak investigation and response for their cooperation. We thank the frontline health workers; Moses Lotee, Clementina Ilukol, and Jane Frances Ocho, whom we worked with during case finding, implementation of public health actions, and enrollment of controls for their time, support and cooperation. We also acknowledge the Ministry of Health through Uganda National Expanded Program on Immunization (UNEPI) for the logistical and technical support to the outbreak response especially the mass measles campaign. Authors’ contribution EM drafted the initial version of the manuscript. RM, BK, LB and ARA revised the manuscript for substantial intellectual content. DW, AN, DS, EK, RA, and RM participated in the outbreak investigation. RM also supervised the field data collection and reviewed the draft manuscript for substantial intellectual content. All authors read and approved the final manuscript. Funding This study was supported by the President’s Emergency Plan for AIDS Relief (PEPFAR) through the United States Centers for Disease Control and Prevention Cooperative Agreement number GH001353-01 through Makerere University School of Public Health to the Uganda Public Health Fellowship Program, Ministry of Health. The contents of this manuscript are solely the responsibility of the authors and do not necessarily represent the official views of the US Centers for Disease Control and Prevention and the Department of Health and Human Services, Makerere University School of Public Health, or the Uganda Ministry of Health. Availability of data and materials The datasets generated and/or analyzed during this investigation are not publicly available as they are property of MoH of Uganda and the Uganda Public Health Fellowship Program (UPHFP) but are available upon reasonable request from the corresponding author (Emmanuel Mfitundinda), email: [email protected] ) and with permission from MoH and UPHFP Consent for publication Not applicable. Competing interests All authors declare that they have no competing interests. Clinical trial number Not applicable References WHO. Measles vaccines: WHO position paper, April 2017 – Recommendations. Vaccine. 2019;37(2):219–22. Measles [Internet]. [cited 2024 Jul 15]. Available from: https://www.who.int/news-room/fact-sheets/detail/measles Moss WJ, Measles. Lancet. 2017;390(10111):2490–502. WHO. Global childhood immunization levels stalled in 2023, leaving many without life-saving protection [Internet]. [cited 2024 Jul 15]. Available from: https://www.who.int/news/item/15-07-2024-global-childhood-immunization-levels-stalled-in-2023-leaving-many-without-life-saving-protection Minta AA. Progress Toward Measles Elimination — Worldwide, 2000–2022. MMWR Morb Mortal Wkly Rep [Internet]. 2023 [cited 2024 Jul 15];72. Available from: https://www.cdc.gov/mmwr/volumes/72/wr/mm7246a3.htm WHO U. WHO and UNICEF estimates of immunization coverage [Internet]. 2024 Jul. Available from: https://data.unicef.org/wp-content/uploads/cp/immunisation/uga.pdf AFENET. Uganda’s Moroto and Sembabule districts battle Measles outbreak: Investigation and response ongoing [Internet]. AFENET. 2024 [cited 2024 Jul 27]. Available from: https://afenet.net/measles-outbreak-investigation-in-moroto-and-sembabule-districts/ Okiror Okello E, Migisha R, Ampaire I, Nsubuga F, Nalwanga J, Kwizera P, et al. Measles outbreak investigation in Kakumiro District, Uganda, February–May 2024. Discov Public Health. 2025;22(1):52. Uganda Bureau of Statistcs. 2023. Uganda Demographic and Health Survey 2022. Kampala, Uganda. Map Uganda -. Popultion density by administrative division [Internet]. [cited 2024 Oct 28]. Available from: http://www.geo-ref.net/ph/uga.htm Uganda Radionetwork [Internet]. [cited 2024 Jul 19]. Insecurity: Operations of Three Schools In Moroto Suspended: Available from: https://ugandaradionetwork.net/story/moroto-operations-of-three-schools-suspened-over-insecurity- Oyel R, Nilepost N. 2024 [cited 2024 Jul 19]. Death toll in Moroto warrior attacks increases to 11. Available from: https://nilepost.co.ug/crime/206192/death-toll-in-moroto-warrior-attacks-increases-to-11 WHO Afro. OMS | Escritório Regional para a África. 2024 [cited 2024 Jul 16]. Outbreak and other Emergencies: Week 23: 3–9 June 2024. Available from: https://www.afro.who.int/countries/kenya/publication/outbreak-and-other-emergencies-week-23-3-9-june-2024 Bawa S, Afolabi M, Abdelrahim K, Abba G, Ningi A, Tafida SY, et al. Transboundary nomadic population movement: a potential for import-export of poliovirus. BMC Public Health. 2018;18(4):1316. Kamadjeu R, Mulugeta A, Gupta D, Abshir Hirsi A, Belayneh A, Clark-Hattingh M, et al. Immunizing nomadic children and livestock – Experience in North East Zone of Somalia. Hum Vaccines Immunotherapeutics. 2015;11(11):2637–9. Schelling E, Bechir M, Ahmed MA, Wyss K, Randolph TF, Zinsstag J. Human and Animal Vaccination Delivery to Remote Nomadic Families, Chad. Emerg Infect Dis. 2007;13(3):373–9. Akinloluwa OO, Lokossou V, Okatubo G, Okunromade O, Nwitte-Eze O, Alabi S, et al. Towards a multi-lateral framework for cross-border surveillance and information sharing between Nigeria and neighbouring countries. BMJ Global Health. 2024;9(3):e013011. Biribawa C, Atuhairwe JA, Bulage L, Okethwangu DO, Kwesiga B, Ario AR, et al. Measles outbreak amplified in a pediatric ward: Lyantonde District, Uganda, August 2017. BMC Infect Dis. 2020;20(1):398. Nosocomial transmission of. measles: An updated review. Vaccine. 2012;30(27):3996–4001. Farizo: Pediatric emergency room visits: a risk factor… Google Scholar [Internet].[cited 2024 Jul 19]. Available from: https://scholar.google.com/scholar_lookup?&title=Pediatric%20emergency%20room%20visits%3A%20a%20risk%20factor%20for%20acquiring% 20measles&journal=Pediatrics&volume=87&issue=1&pages=74-79&publication_year=1991&author=Farizo%2CKM&author=Stehr-Green%2CPA&author=Simpson%2CDM&author=Markowitz%2CLE. Biellik RJ, Clements CJ. Strategies for minimizing nosocomial measles transmission. Bull World Health Organ. 1997;75(4):367–75. Ayele WM. Malnutrition Precipitated Measles Outbreak in Gewane District, Afar Regional State, Northeastern Ethiopia, 2016 [Internet]. 2020 [cited 2024 Jul 19]. Available from: https://www.researchsquare.com/article/rs-32423/v1 Nassar AAH, Al Amad MA, Qasim M, Dureab F. Risk factors for measles outbreak in Ataq and Habban districts, Shabwah governorate, Yemen, February to May 2018. BMC Infect Dis. 2021;21(1):551. Uganda -, Karamoja, IPC Acute Food Insecurity and Acute, Malnutrition Analysis. March 2024 - February 2025 (Issued 12 June 2024) - Uganda | ReliefWeb [Internet]. 2024 [cited 2024 Jul 19]. Available from: https://reliefweb.int/report/uganda/uganda-karamoja-ipc-acute-food-insecurity-and-acute-malnutrition-analysis-march-2024-february-2025-issued-12-june-2024 Salama P, Assefa F, Talley L, Spiegel P, van der Veen A, Gotway CA. Malnutrition, Measles, Mortality, and the Humanitarian Response During a Famine in Ethiopia. JAMA. 2001;286(5):563–71. Tran IC, Gregory C, O’Connor P, Imohe A, Do LAH, Suchdev PS. A scoping review on the associations and potential pathways between malnutrition and measles [Internet]. medRxiv; 2023 [cited 2024 Jul 19]. p. 2023.01.21.23284872. Available from: https://www.medrxiv.org/content/ 10.1101/2023.01.21.23284872v1 Patel MK, Orenstein WA. Classification of global measles cases in 2013–17 as due to policy or vaccination failure: a retrospective review of global surveillance data. Lancet Global Health. 2019;7(3):e313–20. Aaby P, Martins CL, Garly ML, Rodrigues A, Benn CS, Whittle H. The optimal age of measles immunisation in low-income countries: a secondary analysis of the assumptions underlying the current policy. BMJ Open. 2012;2(4):e000761. Do LAH, Toh ZQ, Licciardi PV, Mulholland EK. Can early measles vaccination control both measles and respiratory syncytial virus infections? Lancet Global Health. 2022;10(2):e288–92. Lochlainn LMN, de Gier B, van der Maas N, van Binnendijk R, Strebel PM, Goodman T, et al. Effect of measles vaccination in infants younger than 9 months on the immune response to subsequent measles vaccine doses: a systematic review and meta-analysis. Lancet Infect Dis. 2019;19(11):1246–54. Leuridan E, Hens N, Hutse V, Ieven M, Aerts M, Damme PV. Early waning of maternal measles antibodies in era of measles elimination: longitudinal study. BMJ. 2010;340:c1626. Namulondo E, Ssemanda I, Komugisha M, Nuwamanya Y, Nsubuga EJ, Wako S et al. Measles Outbreak in a Refugee Settlement, Kiryandongo District, Uganda, July– October 2023 [Internet]. 2024 [cited 2024 Jul 19]. Available from: https://www.researchsquare.com/article/rs-4497006/v1 Uzicanin A, Zimmerman L. Field Effectiveness of Live Attenuated Measles-Containing Vaccines: A Review of Published Literature. J Infect Dis. 2011;204(suppl1):S133–49. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6106444","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":440705002,"identity":"630079fb-d69a-4f4f-8b8d-24bf2ba72e63","order_by":0,"name":"Emmanuel 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Institute of Public Health","correspondingAuthor":false,"prefix":"","firstName":"Benon","middleName":"","lastName":"Kwesiga","suffix":""},{"id":440705007,"identity":"0104f3c9-c568-4669-b465-63c1abd027b4","order_by":5,"name":"Ruth Ayeerwot","email":"","orcid":"","institution":"Karamoja Regional Emergency Operations Centre","correspondingAuthor":false,"prefix":"","firstName":"Ruth","middleName":"","lastName":"Ayeerwot","suffix":""},{"id":440705008,"identity":"543e4a2e-3c09-4ff9-a8d0-c1b53722cff5","order_by":6,"name":"Emmanuel Korobe","email":"","orcid":"","institution":"Moroto District Local Government","correspondingAuthor":false,"prefix":"","firstName":"Emmanuel","middleName":"","lastName":"Korobe","suffix":""},{"id":440705009,"identity":"372e1713-134b-4f0d-b862-55108c244629","order_by":7,"name":"Druscillah Ssekandi","email":"","orcid":"","institution":"Uganda National Expanded Program on Immunization, Ministry of Health, 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15:08:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6106444/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6106444/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12982-025-00581-y","type":"published","date":"2025-05-16T15:57:46+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":80659698,"identity":"ed1e671e-f198-4822-b857-2d2866b864c4","added_by":"auto","created_at":"2025-04-15 16:18:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":29049,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDistribution of measles cases by the date of onset of symptoms, Moroto District, Uganda, March–September, 2024 (n = 290)\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6106444/v1/d0019646f86a7c3d2041e9fc.png"},{"id":80659707,"identity":"5894e75e-3d17-4416-b3d6-6264606f931c","added_by":"auto","created_at":"2025-04-15 16:18:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":6852,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eClinical features of measles case-patients, Moroto District, Uganda, March–September, 2024\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6106444/v1/e12fdb38359e3090bdeecb02.png"},{"id":80660780,"identity":"da843161-21e7-4cc5-8b11-060aa8f04b2b","added_by":"auto","created_at":"2025-04-15 16:26:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":102422,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAttack Rate (per 10,000) by sub-county of residence in measles outbreak, Moroto District, Uganda, March–September, 2024\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6106444/v1/6a748b743436b6be38580dee.png"},{"id":80659709,"identity":"430db726-7210-4d13-8a89-032c5cd5c8f7","added_by":"auto","created_at":"2025-04-15 16:18:21","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":12716,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003evaccination coverage by administrative unit in measles outbreak, Moroto District, Uganda, March–September, 2024\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6106444/v1/eed1d2297558b9743966af29.png"},{"id":83067848,"identity":"afb506db-20d6-4eac-8523-7e9bfd3cae55","added_by":"auto","created_at":"2025-05-19 16:06:56","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1248349,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6106444/v1/f0554750-7d31-4de4-a91c-6b4dd0fb5dc7.pdf"},{"id":80659699,"identity":"b04deb4f-c15c-4f58-acdd-a9513316bd7f","added_by":"auto","created_at":"2025-04-15 16:18:21","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":24823,"visible":true,"origin":"","legend":"","description":"","filename":"Appendix1.docx","url":"https://assets-eu.researchsquare.com/files/rs-6106444/v1/055d3cd400c5c0549af72022.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Investigation of a cross-border measles outbreak in Moroto District, northeastern Uganda, March–September, 2024","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMeasles is a highly contagious, vaccine-preventable viral disease primarily affecting children\u0026thinsp;\u0026lt;\u0026thinsp;5 years, with a case fatality rate (CFR) of 5\u0026ndash;10% [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The incubation period of measles is 7\u0026ndash;21 days [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The disease presents with fever, maculopapular rash, cough, and conjunctivitis. Severe complications such as pneumonia, diarrhea, and encephalitis are more likely in malnourished children, those with advanced HIV, and those living in overcrowded conditions [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Measles remains one of the leading causes of morbidity and mortality worldwide with 103 countries reporting outbreaks and an increase in measles related deaths from 95,000 in 2021 to 136,200 in 2023 [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. This resurgence was a result of a decline in vaccination coverage worldwide. The decline in vaccination coverage was exacerbated by the emergence of the COVID-9 pandemic that ravaged the health systems globally. Globally the first dose of Measles Containing Vaccine (MCV) coverage declined from 86% in 2019 to 81% in 2021 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe World Health Organization (WHO) recommends two doses of MCV with the first dose administered between 9 and 12 months of age and the second dose administered at the age of 15\u0026ndash;18 months of age, the second dose should be at least one month apart from the first one [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In Uganda, the first dose of measles (MCV1) coverage was 85% in 2022, while the second dose (MCV2), introduced in 2022, remains suboptimal at 44% [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. To achieve herd immunity and prevent outbreaks, coverage should exceed 93% at the district level. Due to low MCV coverage, in 2024 alone, by mid-year, Uganda had experienced 20 measles outbreaks across various districts [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOn June 26, 2024, the Uganda Ministry of Health (MoH) through the National Public Health Emergency Operations Centre received notification of a measles outbreak in Moroto District, Karamoja Region. Out of thirteen blood samples that were sent to the Uganda Virus Research Institute (UVRI), seven of them tested positive for measles-specific Immunoglobulin M (IgM) antibodies. We investigated the measles outbreak to determine its scope, assess risk factors for transmission, identify the source, and evaluate vaccine effectiveness and coverage, so as to recommend evidence-based control measures and strategies for future prevention.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eOutbreak area\u003c/h2\u003e \u003cp\u003eWe conducted the investigation in Moroto District in Karamoja Region, northeastern Uganda. This region is inhabited by the Karamojong who are predominantly nomadic pastoralists. The district neighbours the Turkana Region of Kenya which is also occupied by nomadic pastoralists known as the Turkana people. Both people have intertwined cultures with a lot in common. In 2024, the estimated population of Moroto District was 128,800, with a low population density of less than 50 people per km\u0026sup2; [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The district is divided into six sub-counties, one town council, and a municipality with two divisions. Moroto District has 18 health facilities, 17 of which provide immunization services. These include one regional referral hospital, six Health Centers III (HC IIIs), and 11 Health Centers II (HC IIs). St. Pius Kidepo HC III is the only private non-for-profit (PNFP) facility, while the rest are public health facilities. All but one health facility offers immunization services, with both static and outreach services available.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCase definition and case finding\u003c/h3\u003e\n\u003cp\u003eWe defined a suspected case as onset of fever and maculopapular rash and one or more of the following symptoms: cough, runny nose or conjunctivitis in a resident of Moroto District from March 15, 2024 to September 24, 2024. A confirmed case was a suspected case with positive results for IgM measles-specific antibody test in a resident of Moroto District.\u003c/p\u003e \u003cp\u003eWe line-listed suspected measles cases by reviewing health facility records at Moroto Regional Referral Hospital (RRH) and St. Pius, Kidepo HC III because the rest of the health facilities were inaccessible due to insecurity that was ongoing in the area [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Line-listing involved compiling detailed information on each suspected case, including demographic and clinical data. Additional cases were identified through collaboration with Health Facility Surveillance Focal Persons (HFSFPs), who reviewed records at facilities that we were unable to reach due to security challenges and subsequently provided the line-lists. The HFSFP shared the updated line-lists via email on a daily basis. Data on demographics, clinical characteristics, vaccination status, exposure history, treatment and admission history were collected using standard case investigation forms (\u003cem\u003eSupplementary material: Appendix 1\u003c/em\u003e).\u003c/p\u003e\n\u003ch3\u003eLaboratory investigations\u003c/h3\u003e\n\u003cp\u003eSamples of whole blood were collected from 21 suspected case-patients and sent to Uganda Virus Research Institute (UVRI) for Measles specific IgM testing.\u003c/p\u003e\n\u003ch3\u003eDescriptive epidemiology\u003c/h3\u003e\n\u003cp\u003eWe constructed an epidemic curve to assess the temporal distribution of measles cases. We computed attack rates (ARs) by person, and place using based on the 2024 projected populations from the Uganda National Bureau of Statistics (UBOS) 2014 census as the denominator and presented the results using tables. Distribution of cases by place was further illustrated on maps using Quantum Geographic Information System (QGIS).\u003c/p\u003e\n\u003ch3\u003eEnvironmental assessment\u003c/h3\u003e\n\u003cp\u003eWe made an observational assessment of the pediatric outpatient department, inpatient ward and the designated isolation ward to understand the flow of the patients and observe for possible risk factors for nosocomial spread. We assessed the outpatient and the in-patient registers to assess reasons for attendance and admission. Additionally, we also screened the patients for symptoms of measles.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eHypothesis generation\u003c/h2\u003e \u003cp\u003eWe conducted 30 hypothesis generating interviews from suspected case-patients using the measles case investigation form. The interviews were among the initial case-patients that we were able to reach at the start of our investigation. The hypothesis-generating interviews were conducted to identify possible risk factors and inform further investigation into the source and spread of the outbreak. Caretakers were asked about potential exposures in the three weeks prior to the onset of symptoms, including visits to health facilities, lack of vaccination, hosting visitors from Kenya or neighboring districts, and travel outside the district. Child health cards were used as the primary source of vaccination information; when unavailable, caretaker recall was relied upon, which was further validated by asking for vaccination site and age at vaccination. Interviews were also conducted with the District Health Team (DHT) to explore potential exposure factors and identify the source of the outbreak.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCase-control study\u003c/h3\u003e\n\u003cp\u003eWe conducted a matched case-control study to evaluate our hypotheses. We recruited 83 case patients who had been line listed by the time of the case-control study. For each case, two controls were selected, aged 6 months to 5 years, with no history of fever, rash, or conjunctivitis between March 15 and July 23, 2024. Controls had an alternative diagnosis confirmed by either a pediatrician or a medical officer and were residents of Moroto District. They were selected consecutively from the pediatric inpatient and outpatient wards upon exiting the consultation room. Data were collected using KoboToolTM, with analysis conducted using Epi Info 7.1.5 (CDC, Atlanta, USA). To assess the risk factors for measles infection, adjusted odds ratios (aOR) and their corresponding 95% confidence intervals (CIs) were calculated. Factors found to be statistically significant (p value\u0026thinsp;\u0026lt;\u0026thinsp;0.05) in bivariate analysis were included in the multivariable logistic regression analysis.\u003c/p\u003e\n\u003ch3\u003eVaccine coverage\u003c/h3\u003e\n\u003cp\u003eWe estimated the vaccine coverage (VC) using the percentage of controls with a history of measles vaccination in the case control study, under the assumption that the controls were representative of the general population. For MCV-1, the VC was determined by dividing the number of eligible controls who were vaccinated by the total number of eligible controls. For overall VC, the calculation was based on the total number of controls, with the numerator being the number of controls who had received the vaccination. Additionally, we extracted data from the national health information database software, DHIS2 for the vaccination coverage that was reported for the district\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eVaccine Effectiveness\u003c/h2\u003e \u003cp\u003eVaccine effectiveness (VE) was estimated among the case-control participants to assess the vaccine\u0026rsquo;s effectiveness in preventing measles during the outbreak. We calculated VE using the formula:\u003c/p\u003e \u003cp\u003eVE\u0026thinsp;=\u0026thinsp;1- aOR\u003c/p\u003e \u003cp\u003eWhere aOR is the odds ratio associated with having been vaccinated with at least one dose of measles vaccine, adjusted for risk factors that were significant during the univariate analysis, using logistic regression.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eDescriptive epidemiology\u003c/h2\u003e \u003cp\u003eWe identified 290 case-patients (275 suspected cases, 15 confirmed cases. During this outbreak 6 deaths were recorded. The index case-patient, was a 10-month-old child from Kosiroi Village in Tapac Sub-county, located near the Kenyan border in the Western Turkana Region. This child had received one dose of the measles-containing vaccine (MCV) and had returned from Kenya on April 1, 2024, where a measles outbreak was ongoing, just four days before symptoms began. This region had an ongoing measles outbreak. The child visited Moroto RRH on April 5, 2024 and came into contact with other children, after which more cases were reported from other sub-counties. The second case-patient was a two-year-old female from Lotisan sub-county who had initially visited the health facility on the same day as the index case-patient. The third case-patient was from the neighborhood of the second case-patient in Lotisan sub-county. From this point onwards, the epidemic curve showed a propagated pattern with multiple peaks over the outbreak period (Fig.\u0026nbsp;1). There was delay in receiving laboratory results of measles IgM, which took two months to be made available to the district. On June 23, 2024, a separate isolation unit was designated at the hospital for the measles cases. Six deaths were recorded, all occurring at Moroto RRH (MRRH). The deceased died from complications of severe pneumonia, with underlying malnutrition. Three of the deaths were among children unvaccinated against measles, and three had an unknown vaccination status. \u003cb\u003eFigure 1: Distribution of measles cases by the date of onset of symptoms, Moroto District, Uganda, March\u0026ndash;September, 2024 (n\u0026thinsp;=\u0026thinsp;290)\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAll cases presented with fever and generalized rash. The majority of the cases had running nose (71%), and red eyes (67%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Other symptoms were cough, diarrhea, generalized body weakness, poor feeding. 22% (52/236) of the cases had complications. The common complications during this outbreak were diarrhea (16%), diarrhea and pneumonia (3%), and pneumonia alone (2.5%).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe most affected age group was \u0026lt;\u0026thinsp;1 year of age (194/10,000) followed by the 1\u0026ndash;4 years age group (47/10, 0000), and 5\u0026ndash;15 years (2/10,000). The AR was similar among males (20/10,000) and females (18/10,000) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMeasles AR by age group during a measles outbreak, Moroto District, Uganda, March\u0026ndash;September 2024\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCategory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePopulation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eAR/10,000\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1 year\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e103\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5,306\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e194\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u0026ndash;4 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e118\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25,297\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u0026ndash;15 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64,168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e106\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59,200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e130\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64,600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe most affected sub-counties were Lotisan (50/10,000) and Rupa (41/10,000). These were followed by Nandunget (17/10,000), Northern Division (14/10,000), Loputuk (13/10,000), Katikekile (9/10,000), Southern Division (7/10,000), and Tapac (1/10,000) sub-counties. The overall AR was 19/10,000 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eEnvironmental findings\u003c/h2\u003e \u003cp\u003ePrior to the confirmation of the outbreak, measles case-patients were being treated alongside other patients in the same wards. After the confirmation of the outbreak by the district, an isolation ward was designated at Moroto RRH and then much later as a result of increase in cases at St. Pius Kidepo HC III. There was free mixing of suspected measles case-patients and non-measles patients in the pediatric out patients.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eHypothesis generation findings\u003c/h2\u003e \u003cp\u003eOf the 30 cases-patients, 25 (83%) were not vaccinated, 19 (63%) had visited a health facility, 8 (27%) were malnourished, and 2 (7%) had received a visitor from a neighboring district.\u003c/p\u003e \u003cp\u003eInterviews with the district health officer, and district surveillance focal person (DSFP) revealed that there was frequent movement across the Ugandan border with Kenya and they had been on high alert since the beginning of the year following information from the Kenyan public health officials about a measles outbreak that was ongoing in the Western Turkana Region.\u003c/p\u003e \u003cp\u003eWe hypothesized that the spread of the outbreak was facilitated by factors including sub-optimal vaccination coverage, travel to a neighboring country, malnutrition, and prior visits to health facilities before the onset of symptoms.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eCase-control study findings, vaccine coverage and vaccine effectiveness\u003c/h2\u003e \u003cp\u003eAt multivariable analysis, lack of vaccination against measles (aOR\u0026thinsp;=\u0026thinsp;8.9, 95%CI\u0026thinsp;=\u0026thinsp;2.5\u0026ndash;32), malnutrition (aOR\u0026thinsp;=\u0026thinsp;6.1, 95%CI\u0026thinsp;=\u0026thinsp;1.3\u0026ndash;27), and visiting a health facility during exposure period (aOR\u0026thinsp;=\u0026thinsp;3.8, 95%CI\u0026thinsp;=\u0026thinsp;1.3\u0026ndash;11) were significantly associated with measles transmission (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cem\u003e).\u003c/em\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFactors associated with measles transmission during the outbreak in Moroto District, Uganda, March\u0026ndash;September 2024\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRisk factor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCases\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControls\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCrude OR\u003c/p\u003e \u003cp\u003e(95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eaOR\u003c/p\u003e \u003cp\u003e(95%CI)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLack of Vaccination\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10 (4.2\u0026ndash;23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.9 (2.5\u0026ndash;32)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e111 (9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMalnutrition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24 (29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24 (15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.4 (1.3\u0026ndash;4.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.1 (1.3\u0026ndash;27)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59 (71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e142 (85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003e*Visiting a health facility during exposure period\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37 (45)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14 (18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.6 (1.7\u0026ndash;7.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.8 (1.3\u0026ndash;11)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46 (55)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63 (82)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVisitor from another district\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.7 (1.1\u0026ndash;6.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.9 (0.3\u0026ndash;53)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e72 (87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e157 (95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVitamin A in the last 6 months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69 (83)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e153 (92)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.42 (0.19\u0026ndash;0.95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.5 (0.1\u0026ndash;3.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*Exposure period was defined as 21 days prior to onset of rash; Ref: Reference category; OR: Odds ratio; aOR: Adjusted odds ratio; CI: Confidence interval\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEstimation of vaccine coverage and effectiveness during measles outbreak in Moroto District, Uganda, March\u0026ndash;September 2024\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRisk factor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCases\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControls\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCrude OR\u003c/p\u003e \u003cp\u003e(95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eaOR\u003c/p\u003e \u003cp\u003e(95%CI)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVaccination\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e111 (91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.099 (0.04\u0026ndash;0.26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.11 (0.03\u0026ndash;0.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eRef: Reference category; OR: Odds ratio; aOR: Adjusted odds ratio; CI: Confidence interval\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe estimated VE was 89% (95% CI\u0026thinsp;=\u0026thinsp;60\u0026ndash;97). The estimated VC, based on the percent of controls that had a history of being vaccinated against measles, was 91% among those\u0026thinsp;\u0026ge;\u0026thinsp;9 months of age and 67% for all the controls regardless of eligibility.\u003c/p\u003e \u003cp\u003eThe VC from DHIS2 showed the overall VC for the district was 77% for MCV1 and 15% for MCV2. It varied for the different sub-counties with Rupa with the lowest MCV1 coverage of 29% and Southern Division with the lowest MCV2 coverage of 4% (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur investigation revealed that the measles outbreak was likely introduced from the neighboring Turkana Region in Western Kenya, which had been experiencing a large outbreak. Vaccination provided strong protection against the disease, while visits to healthcare facilities during exposure period and malnutrition were associated with an increased risk of measles infection. The estimated vaccine coverage was 67% and vaccine effectiveness of 89%. Rupa Sub-county, with the lowest vaccine coverage had the highest attack rate. Overall, these findings emphasize the need for enhanced vaccination efforts.\u003c/p\u003e \u003cp\u003eThis measles outbreak was likely introduced through cross-border transmission from the Western Turkana Region, which had been experiencing a measles outbreak since December 2023 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Both regions are home to nomadic pastoralist communities that frequently cross the border for cultural and grazing activities, a phenomenon that has previously been implicated in the spread of vaccine-preventable diseases [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Evidence from other regions, such as Somalia and Chad, suggests that integrating animal vaccination programs with human vaccination initiatives could improve coverage within such nomadic populations [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. To prevent future outbreaks, enhancing cross-border information sharing at both the district and regional levels, along with strengthening surveillance at border points, is critical to mitigate the risks posed by cross-border movements [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe outbreak was further facilitated by the mixing of measles and non-measles patients before the outbreak was confirmed and an isolation unit established at Moroto RRH. Nosocomial transmission has been a known factor in measles outbreaks [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The highly contagious nature of measles, along with its infectious period before the onset of classic symptoms like rash and fever, makes implementing screening and isolation protocols particularly challenging. The WHO recommends that vaccination should also be offered to all exposed, non-immune children within 72 hours of exposure for effective protection [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Strengthening screening protocols at healthcare facilities, combined with the timely isolation of suspected measles cases, could minimize nosocomial transmission in future outbreaks.\u003c/p\u003e \u003cp\u003eMalnutrition, which is highly prevalent in this outbreak area was associated with increased odds of measles infection. Studies in Afar District of north eastern Ethiopia and Yemen found similar findings with malnutrition increasing the odds of measles disease [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. This area had been experiencing an increase in acute food insecurity and malnutrition levels during the period of the outbreak [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Malnutrition also heightens the risk of mortality in children with measles; in this study, all five recorded deaths had malnutrition as an underlying condition. These findings align with other studies conducted in the Horn of Africa and beyond [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. To mitigate the impact of future similar outbreaks, and reduce measles-associated mortality in vulnerable communities, district authorities should consider addressing food insecurity and malnutrition as part of the broader public health response.\u003c/p\u003e \u003cp\u003eVaccination was protective against measles disease. Measles vaccination is globally recognized as the primary strategy for preventing outbreaks and ultimately achieving disease elimination. The WHO recommends two doses of MCV with the first dose administered at 9 months and the second dose at 15\u0026ndash;18 months of age, and a VC of at least 80% for MCV2 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, our findings revealed a high attack rate among children1 year, suggesting the need for policy revision to target children as young as 6 months for the first MCV dose. A global review of measles cases between 2013 and 2017 indicated that 13% of all measles cases in Sub-Saharan Africa occurred among children who were not eligible for MCV, recommending a country-level data analysis and potential revision of immunization strategies to lower the age for the first MCV dose [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. However, there are concerns on the immunogenicity of MCV administered at \u0026lt;\u0026thinsp;9 months and WHO recommends MCV at 6 months only during high risk period. Children who get MCV at 6 months during the high risk period are recommended to follow the normal schedule for the subsequent MCV doses [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Some studies have demonstrated good immunogenicity when MCV was administered at \u0026lt;\u0026thinsp;9 months with subsequent protective effect against measles outbreaks [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Maternal antibodies have also been found to wane much earlier and unable to provide protection to infants beyond the 6 months of age [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. To prevent and control future outbreaks, it is essential to strengthen and support routine vaccination programs, and consider revising the national immunization schedule to administer the first MCV dose at 6 months of age.\u003c/p\u003e \u003cp\u003eOur investigation found an estimated VE of 89%. This was higher than in a previous study that found a VE 85%, but lower than in another study in Uganda that found a VE of 95% [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. However, the VE was within the range of findings of systematic review of measles that found a median VE of 77%, with an (interquartile range [IQR] of 62\u0026ndash;91) % when MCV1 was administered at 9\u0026ndash;11 months. Administration of MCV1 at \u0026ge;\u0026thinsp;12 months resulted in higher VE (median of 92%, IQR [86\u0026ndash;96%]). VE findings from the field vary and depend on the number of doses administered, vaccine handling and storage, cold chain failure and host factors such as malnutrition and HIV infection [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. We recommend strengthening of the vaccination program in the district with emphasis on MCV2 to further improve the VE.\u003c/p\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eStudy limitations\u003c/h2\u003e \u003cp\u003eThe outbreak investigation had some limitations. There was ongoing insecurity in the most affected communities of Lotisan and Rupa Sub-counties of the district during this outbreak [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. We could not access the affected communities, this could have led to underestimation of the magnitude of the outbreak and also interviewing more severe case-patients who were more likely to seek care. We enrolled hospital controls which was also as a result of the insecurity that was ongoing and there is a possibility that this could have introduced a misclassification bias. The bias was minimized by cautious selection of the controls and only considering those without symptoms of measles and with a diagnosis other than measles made by either a pediatrician or a medical officer at the hospital.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis measles outbreak was likely introduced from the Western Turkana Region of Kenya to Moroto District, Karamoja Region, through cross-border movement. The outbreak was propagated by the mixing of case-patients with other children seeking care at various health facilities, facilitating nosocomial transmission. Additionally, malnutrition and low measles vaccination coverage in the area contributed to the spread of the outbreak. To mitigate the risk of future outbreaks, it is essential to improve vaccination coverage, strengthen triage systems at health facilities for early case detection and management, and improve cross-border surveillance. Additionally, it is essential to address malnutrition and food insecurity in regions vulnerable to measles outbreaks for better public health outcomes.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eaOR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAdjusted Odds Ratio\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAttack Rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCDC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCenters for Disease Control and Prevention\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCFR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCase Fatality Rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDHIS2\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDistrict Health Information System 2\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDHT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDistrict Health Team\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eEOC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEmergency Operations Centre\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eHFSFP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHealth Facility Surveillance Focal Person\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eHC II\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHealth Center II\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eHC III\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHealth Center III\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIgM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eImmunoglobulin M\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMCV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMeasles Containing Vaccine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMCV1\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFirst dose of Measles Containing Vaccine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMCV2\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSecond dose of Measles Containing Vaccine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMoH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMinistry of Health\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRRH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRegional Referral Hospital\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eUVRI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eUganda Virus Research Institute\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eVE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVaccine Effectiveness\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eVC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVaccine Coverage\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eWHO\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eWorld Health Organization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis outbreak investigation was in response to a public health emergency and was therefore determined to be non-research. The Ministry of Health (MoH) gave permission to investigate this outbreak. In agreement with the International Guidelines for Ethical Review of Epidemiological Studies by the Council for International Organizations of Medical Sciences (1991) and the Office of the Associate Director for Science, US CDC/Uganda, it was determined that this activity was not human subject research and that its primary intent was public health practice or disease control activity (specifically, epidemic or endemic disease control activity). This activity was reviewed by the US CDC and was conducted consistent with applicable federal law and CDC policy. §§See, e.g., 45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq. All experimental protocols were approved by the US CDC human subjects review board (The National Institute for Occupational Safety and Health Institutional Review Board) and the Uganda Ministry of Health and were performed in accordance with the Declaration of Helsinki. We sought permission to conduct the investigation from the District health authorities of Moroto District. We obtained verbal consent from the respondents’ parents/caretakers on behalf of their children. We informed the participants that their participation was voluntary and their refusal to participate would not have any negative consequences to them. Before sharing and analyzing the data collaboratively among members of the investigation team, we deleted all identifiable information (i.e., name, address, phone number, etc.).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe acknowledge the support of the Moroto District local government and Karamoja Regional Emergency Operations Centre (EOC) who worked with us during this outbreak investigation and response for their cooperation. \u0026nbsp;We thank the frontline health workers; Moses Lotee, Clementina Ilukol, and Jane Frances Ocho, whom we worked with during case finding, implementation of public health actions, and enrollment of controls for their time, support and cooperation. We also acknowledge the Ministry of Health through Uganda National Expanded Program on Immunization (UNEPI) for the logistical and technical support to the outbreak response especially the mass measles campaign.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEM drafted the initial version of the manuscript. RM, BK, LB and ARA revised the manuscript for substantial intellectual content. DW, AN, DS, EK, RA, and RM participated in the outbreak investigation. RM also supervised the field data collection and reviewed the draft manuscript for substantial intellectual content. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the President’s Emergency Plan for AIDS Relief (PEPFAR) through the United States Centers for Disease Control and Prevention Cooperative Agreement number GH001353-01 through Makerere University School of Public Health to the Uganda Public Health Fellowship Program, Ministry of Health. The contents of this manuscript are solely the responsibility of the authors and do not necessarily represent the official views of the US Centers for Disease Control and Prevention and the Department of Health and Human Services, Makerere University School of Public Health, or the Uganda Ministry of Health.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during this investigation are not publicly available as they are property of MoH of Uganda and the Uganda Public Health Fellowship Program (UPHFP) but are available upon reasonable request from the corresponding author (Emmanuel Mfitundinda), email:\u0026nbsp;[email protected]\u0026nbsp;) and with permission from MoH and UPHFP\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003e\u003cspan\u003eWHO. Measles vaccines: WHO position paper, April 2017 \u0026ndash; Recommendations. Vaccine. 2019;37(2):219\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMeasles [Internet]. [cited 2024 Jul 15]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.who.int/news-room/fact-sheets/detail/measles\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMoss WJ, Measles. Lancet. 2017;390(10111):2490\u0026ndash;502.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWHO. Global childhood immunization levels stalled in 2023, leaving many without life-saving protection [Internet]. [cited 2024 Jul 15]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.who.int/news/item/15-07-2024-global-childhood-immunization-levels-stalled-in-2023-leaving-many-without-life-saving-protection\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMinta AA. Progress Toward Measles Elimination \u0026mdash; Worldwide, 2000\u0026ndash;2022. MMWR Morb Mortal Wkly Rep [Internet]. 2023 [cited 2024 Jul 15];72. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.cdc.gov/mmwr/volumes/72/wr/mm7246a3.htm\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWHO U. WHO and UNICEF estimates of immunization coverage [Internet]. 2024 Jul. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://data.unicef.org/wp-content/uploads/cp/immunisation/uga.pdf\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eAFENET. Uganda\u0026rsquo;s Moroto and Sembabule districts battle Measles outbreak: Investigation and response ongoing [Internet]. AFENET. 2024 [cited 2024 Jul 27]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://afenet.net/measles-outbreak-investigation-in-moroto-and-sembabule-districts/\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eOkiror Okello E, Migisha R, Ampaire I, Nsubuga F, Nalwanga J, Kwizera P, et al. Measles outbreak investigation in Kakumiro District, Uganda, February\u0026ndash;May 2024. Discov Public Health. 2025;22(1):52.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eUganda Bureau of Statistcs. 2023. Uganda Demographic and Health Survey 2022. Kampala, Uganda.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMap Uganda -. Popultion density by administrative division [Internet]. [cited 2024 Oct 28]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.geo-ref.net/ph/uga.htm\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eUganda Radionetwork [Internet]. [cited 2024 Jul 19]. Insecurity: Operations of Three Schools In Moroto Suspended: Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ugandaradionetwork.net/story/moroto-operations-of-three-schools-suspened-over-insecurity-\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eOyel R, Nilepost N. 2024 [cited 2024 Jul 19]. Death toll in Moroto warrior attacks increases to 11. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://nilepost.co.ug/crime/206192/death-toll-in-moroto-warrior-attacks-increases-to-11\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWHO Afro. OMS | Escrit\u0026oacute;rio Regional para a \u0026Aacute;frica. 2024 [cited 2024 Jul 16]. Outbreak and other Emergencies: Week 23: 3\u0026ndash;9 June 2024. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.afro.who.int/countries/kenya/publication/outbreak-and-other-emergencies-week-23-3-9-june-2024\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBawa S, Afolabi M, Abdelrahim K, Abba G, Ningi A, Tafida SY, et al. Transboundary nomadic population movement: a potential for import-export of poliovirus. BMC Public Health. 2018;18(4):1316.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eKamadjeu R, Mulugeta A, Gupta D, Abshir Hirsi A, Belayneh A, Clark-Hattingh M, et al. Immunizing nomadic children and livestock \u0026ndash; Experience in North East Zone of Somalia. Hum Vaccines Immunotherapeutics. 2015;11(11):2637\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eSchelling E, Bechir M, Ahmed MA, Wyss K, Randolph TF, Zinsstag J. Human and Animal Vaccination Delivery to Remote Nomadic Families, Chad. Emerg Infect Dis. 2007;13(3):373\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eAkinloluwa OO, Lokossou V, Okatubo G, Okunromade O, Nwitte-Eze O, Alabi S, et al. Towards a multi-lateral framework for cross-border surveillance and information sharing between Nigeria and neighbouring countries. BMJ Global Health. 2024;9(3):e013011.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBiribawa C, Atuhairwe JA, Bulage L, Okethwangu DO, Kwesiga B, Ario AR, et al. Measles outbreak amplified in a pediatric ward: Lyantonde District, Uganda, August 2017. BMC Infect Dis. 2020;20(1):398.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eNosocomial transmission of. measles: An updated review. Vaccine. 2012;30(27):3996\u0026ndash;4001.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eFarizo: Pediatric emergency room visits: a risk factor\u0026hellip; Google Scholar [Internet].[cited 2024 Jul 19]. Available from: https://scholar.google.com/scholar_lookup?\u0026amp;title=Pediatric%20emergency%20room%20visits%3A%20a%20risk%20factor%20for%20acquiring%\u003c/span\u003e\u003cbr\u003e\u003cspan\u003e20measles\u0026amp;journal=Pediatrics\u0026amp;volume=87\u0026amp;issue=1\u0026amp;pages=74-79\u0026amp;publication_year=1991\u0026amp;author=Farizo%2CKM\u0026amp;author=Stehr-Green%2CPA\u0026amp;author=Simpson%2CDM\u0026amp;author=Markowitz%2CLE.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBiellik RJ, Clements CJ. Strategies for minimizing nosocomial measles transmission. Bull World Health Organ. 1997;75(4):367\u0026ndash;75.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eAyele WM. Malnutrition Precipitated Measles Outbreak in Gewane District, Afar Regional State, Northeastern Ethiopia, 2016 [Internet]. 2020 [cited 2024 Jul 19]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.researchsquare.com/article/rs-32423/v1\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eNassar AAH, Al Amad MA, Qasim M, Dureab F. Risk factors for measles outbreak in Ataq and Habban districts, Shabwah governorate, Yemen, February to May 2018. BMC Infect Dis. 2021;21(1):551.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eUganda -, Karamoja, IPC Acute Food Insecurity and Acute, Malnutrition Analysis. March 2024 - February 2025 (Issued 12 June 2024) - Uganda | ReliefWeb [Internet]. 2024 [cited 2024 Jul 19]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://reliefweb.int/report/uganda/uganda-karamoja-ipc-acute-food-insecurity-and-acute-malnutrition-analysis-march-2024-february-2025-issued-12-june-2024\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eSalama P, Assefa F, Talley L, Spiegel P, van der Veen A, Gotway CA. Malnutrition, Measles, Mortality, and the Humanitarian Response During a Famine in Ethiopia. JAMA. 2001;286(5):563\u0026ndash;71.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eTran IC, Gregory C, O\u0026rsquo;Connor P, Imohe A, Do LAH, Suchdev PS. A scoping review on the associations and potential pathways between malnutrition and measles [Internet]. medRxiv; 2023 [cited 2024 Jul 19]. p. 2023.01.21.23284872. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.medrxiv.org/content/\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1101/2023.01.21.23284872v1\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003ePatel MK, Orenstein WA. Classification of global measles cases in 2013\u0026ndash;17 as due to policy or vaccination failure: a retrospective review of global surveillance data. Lancet Global Health. 2019;7(3):e313\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eAaby P, Martins CL, Garly ML, Rodrigues A, Benn CS, Whittle H. The optimal age of measles immunisation in low-income countries: a secondary analysis of the assumptions underlying the current policy. BMJ Open. 2012;2(4):e000761.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eDo LAH, Toh ZQ, Licciardi PV, Mulholland EK. Can early measles vaccination control both measles and respiratory syncytial virus infections? Lancet Global Health. 2022;10(2):e288\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eLochlainn LMN, de Gier B, van der Maas N, van Binnendijk R, Strebel PM, Goodman T, et al. Effect of measles vaccination in infants younger than 9 months on the immune response to subsequent measles vaccine doses: a systematic review and meta-analysis. Lancet Infect Dis. 2019;19(11):1246\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eLeuridan E, Hens N, Hutse V, Ieven M, Aerts M, Damme PV. Early waning of maternal measles antibodies in era of measles elimination: longitudinal study. BMJ. 2010;340:c1626.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eNamulondo E, Ssemanda I, Komugisha M, Nuwamanya Y, Nsubuga EJ, Wako S et al. Measles Outbreak in a Refugee Settlement, Kiryandongo District, Uganda, July\u0026ndash; October 2023 [Internet]. 2024 [cited 2024 Jul 19]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.researchsquare.com/article/rs-4497006/v1\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eUzicanin A, Zimmerman L. Field Effectiveness of Live Attenuated Measles-Containing Vaccines: A Review of Published Literature. J Infect Dis. 2011;204(suppl1):S133\u0026ndash;49.\u003c/span\u003e\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Public Health](https://link.springer.com/journal/12982)","snPcode":"12982","submissionUrl":"https://submission.springernature.com/new-submission/12982/3","title":"Discover Public Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Measles, Disease outbreak, Cross-border health surveillance, Vaccine-effectiveness, Vaccine-coverage, Uganda","lastPublishedDoi":"10.21203/rs.3.rs-6106444/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6106444/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eOn June 26, 2024, Ministry of Health was notified of a measles outbreak in Moroto District, northeastern Uganda, which had already resulted in four deaths. We investigated to assess magnitude of the outbreak, identify its source and risk factors, and recommend evidence-based control and prevention measures.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe defined a suspected case as onset of fever and maculopapular rash, and \u0026ge;\u0026thinsp;1 of cough, coryza, or conjunctivitis in a resident of Moroto District from March 15 to September 22, 2024. A confirmed case was a suspected case with a positive measles-specific IgM test. We identified cases using health facility records and active case search within the health facilities. We conducted a hospital-based case-control study with a 1:2 ratio. Controls were children admitted to the pediatric ward with an alternative diagnosis but no history of fever, rash, or conjunctivitis. We used logistic regression to identify risk factors. We estimated the vaccine effectiveness (VE) from adjusted odds ratio (aOR) associated with vaccination (VE\u0026thinsp;=\u0026thinsp;1-aOR) % and vaccination coverage (VC) from percentage of vaccinated controls.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eWe identified 290 case-patients (275 suspected and 15 confirmed), with 6 deaths (case fatality rate [CFR]\u0026thinsp;=\u0026thinsp;2%). The index case-patient was a 10-month-old child who had returned from the Western Turkana Region of Kenya, where a measles outbreak was ongoing. The overall attack rate (AR) was 19/10,000. Lotisan Sub-county (AR\u0026thinsp;=\u0026thinsp;50/10,000) and children\u0026thinsp;\u0026lt;\u0026thinsp;1 year (AR\u0026thinsp;=\u0026thinsp;194/10,000) were the most affected. Being vaccinated was protective (aOR\u0026thinsp;=\u0026thinsp;0.11, 95%CI\u0026thinsp;=\u0026thinsp;0.03\u0026ndash;0.4). Visiting a health facility 7\u0026ndash;21 days before the onset of rash (aOR\u0026thinsp;=\u0026thinsp;3.8, 95%CI\u0026thinsp;=\u0026thinsp;1.3\u0026ndash;11) and having malnutrition (aOR\u0026thinsp;=\u0026thinsp;6.1, 95%CI\u0026thinsp;=\u0026thinsp;1.3\u0026ndash;27) increased the odds of contracting measles. Estimated VC was 67% and VE was 89% (95%CI\u0026thinsp;=\u0026thinsp;60\u0026ndash;97%).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe outbreak was likely imported from Kenya, and was propagated by low vaccination coverage, and healthcare visits within the exposure period. To prevent similar future outbreaks, it is crucial to improve vaccination coverage, strengthen triage systems at health facilities for prompt case identification and management, and enhance cross-border surveillance.\u003c/p\u003e","manuscriptTitle":"Investigation of a cross-border measles outbreak in Moroto District, northeastern Uganda, March–September, 2024","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-15 16:18:16","doi":"10.21203/rs.3.rs-6106444/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-11T12:39:55+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"129038932063871501146836569531508023871","date":"2025-04-10T05:49:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-09T13:14:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"185263077880170156900436079952830854714","date":"2025-04-09T12:48:35+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-09T12:28:50+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-09T11:54:19+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Public Health","date":"2025-04-02T11:43:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Public Health](https://link.springer.com/journal/12982)","snPcode":"12982","submissionUrl":"https://submission.springernature.com/new-submission/12982/3","title":"Discover Public Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f89e0ee5-23e0-40b9-98f2-9f8b9d08c796","owner":[],"postedDate":"April 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-19T16:01:37+00:00","versionOfRecord":{"articleIdentity":"rs-6106444","link":"https://doi.org/10.1186/s12982-025-00581-y","journal":{"identity":"discover-public-health","isVorOnly":false,"title":"Discover Public Health"},"publishedOn":"2025-05-16 15:57:46","publishedOnDateReadable":"May 16th, 2025"},"versionCreatedAt":"2025-04-15 16:18:16","video":"","vorDoi":"10.1186/s12982-025-00581-y","vorDoiUrl":"https://doi.org/10.1186/s12982-025-00581-y","workflowStages":[]},"version":"v1","identity":"rs-6106444","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6106444","identity":"rs-6106444","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}