SEROEPIDEMIOLOGICAL SURVEY AND THE FACTORS ASSOCIATED WITH THE PRESENCE OF MEASLES ANTIBODIES IN A VULNERABLE POPULATION OF BRASÍLIA- BRAZIL, 2021.

SEROEPIDEMIOLOGICAL SURVEY AND THE FACTORS ASSOCIATED WITH THE PRESENCE OF MEASLES ANTIBODIES IN A VULNERABLE POPULATION OF BRASÍLIA- BRAZIL, 2021. | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 17 October 2025 V1 Latest version Share on SEROEPIDEMIOLOGICAL SURVEY AND THE FACTORS ASSOCIATED WITH THE PRESENCE OF MEASLES ANTIBODIES IN A VULNERABLE POPULATION OF BRASÍLIA- BRAZIL, 2021. Authors : Janet Sallis Nimoh Mensah 0000-0003-2111-1714 , Ana Izabel Passarella Texeira , Carolina Carvalho Gontijo , Walter Massa Ramalho , Rafael da Silva Faria [email protected] , Rodrigo Haddad 0000-0003-4699-164X , and Wildo Navegantes de Araújo Authors Info & Affiliations https://doi.org/10.22541/au.176072412.27563722/v1 196 views 149 downloads Contents Abstract INTRODUCTION/BACKGROUND METHODS Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Measles remains one of the most contagious viral diseases worldwide, yet it is preventable through vaccination. Despite substantial progress achieved through global and national immunization initiatives, including Brazil’s National Immunization Program, declining vaccine coverage in recent years has renewed the risk of outbreaks. This study aimed to estimate the seroprevalence of antibodies against measles virus in SCIA-Estrutural, an administrative region of the Federal District of Brazil characterized by socioeconomic vulnerability. An analytical cross-sectional seroepidemiological survey was conducted between June and November 2021, involving 890 participants with valid serological results. Blood samples were tested for measles-specific IgG antibodies using ELISA, and sociodemographic and vaccination data were collected through structured interviews. Overall seroprevalence was 71.1% (95% CI: 68.1–74.1), below the threshold (>95%) required to prevent viral circulation. Seroprevalence was significantly higher in older age groups, suggesting natural infection prior to widespread vaccination, whereas younger groups showed lower immunity, reflecting recent declines in vaccine coverage. Lower educational attainment was associated with higher seropositivity (p = 0.004), while income showed a borderline association (p = 0.053). Interestingly, individuals in larger households exhibited lower seroprevalence (p < 0.001), suggesting demographic influences on immunity patterns. Possession of a vaccination card (p = 0.024) and history of measles infection (p < 0.001) were positively associated with seropositivity. These findings highlight immunity gaps among younger and socioeconomically diverse groups, emphasizing the urgent need to strengthen vaccination programs, improve outreach in vulnerable communities, and ensure sustained population protection to prevent future measles outbreaks in Brazil . INTRODUCTION/BACKGROUND Measles is an infectious viral disease and one of the most contagious diseases worldwide (WHO, 2025). However, it can be effectively controlled through appropriate measures such as vaccination, early treatment, and quarantine (Khan et al., 2025). Among these, vaccination stands out as the most efficient strategy. Since humans are the only hosts of the measles virus, maintaining high vaccination coverage and adequate antibody titers prevents viral transmission, as the pathogen cannot find susceptible hosts to multiply and persist. For this reason, measles is classified as a vaccine-preventable disease, and both national and global programs adopt immunization as the main strategy to reduce its incidence worldwide. Maintaining measles antibody levels at protective thresholds (>95%) through active immunization strategies is essential (PAHO, 2025). Global and national immunization initiatives, such as the World Health Organization’s Expanded Program on Immunization (EPI) and Brazil’s National Immunization Program (NIP), have reshaped the epidemiology of vaccine-preventable diseases. Their impact has been remarkable: measles incidence decreased by 88% from 2000 (145 cases per 1 million population) to 2016 (18 cases per 1 million), while measles mortality fell by 73% between 2000 (536,000 deaths) and 2018 (142,000 deaths). These efforts prevented an estimated 23.2 million deaths globally, most of them in Africa (Domingues et al., 2013; Patel et al., 2020; Fiocruz, 2025). Despite these efforts, vaccine coverage has been declining across several countries. In 2019 alone, approximately 207,000 deaths from measles were associated with insufficient global vaccination coverage. The COVID-19 pandemic further exacerbated this problem by interrupting routine immunization campaigns and delaying childhood vaccination programs, leading to larger clusters of susceptible individuals. In some low- and middle- income countries, coverage of the first dose of the measles-containing vaccine (MCV1) has dropped below 80%, whereas the threshold required to prevent outbreaks is at least 95%. This sustained decline in coverage increases the likelihood of large, recurring outbreaks, even in regions where endemic transmission had already been eliminated (GBD 2023). Within the context of this nationwide challenge, the Federal District of Brazil did not remain untouched by the resurgence of measles, and it is therefore pertinent to explore, analyze and investigate how changes in the provision of health services in the country might have affected the population in question - SCIA- Estrutural. METHODS Study design This analytical cross-sectional seroepidemiological survey was conducted between June 21 and November 2021 to estimate the seroprevalence of antibodies against the measles virus in the population of SCIA-Estrutural, Federal District, Brazil, a city located near the country’s capital, Brasília. The study protocol, including the collection of primary data and biological samples, was approved by the Research Ethics Committee of the Faculty of Medicine, University of Brasília (CEP-FM/UnB), under registration numbers CAAE 39866620.4.0000.5558, CAAE 39892420.7.1001.5558, and CAAE 40557020.6.3001.5553. All participants were volunteers and provided written informed consent after being informed about the study objectives, procedures, potential risks, and guarantees of data confidentiality. For individuals under 18 years of age or with disabilities, consent was additionally obtained from parents or legal guardians, while assent was also sought from the participants themselves whenever applicable. Participants’ data were handled with strict confidentiality, with no disclosure to third parties. The study was carried out in full compliance with the Ethical Principles for Medical Research Involving Human Subjects, as outlined in the Declaration of Helsinki, and in accordance with Resolution no. 466/2012 of the National Health Council of Brazil, which establishes the ethical and scientific principles governing research involving human subjects. General setting The location of the study area was the largest refuse disposal site in Latin America, situated near Brasília, approximately 20 km from the presidential palace. Its’ official name is Setor Complementar de Indústria e Abastecimento (Complementary Industry and Supply Sector), known as SCIA Estrutural. It is one of the newest administrative regions (AR) in the Federal District of Brasilia, and before it became an AR, it was mostly inhabited by people collecting recyclable materials, who migrated mostly from the North and Northeast of the country. Till today, this region has been recognized for its environmental and urban vulnerabilities (Boadle, 2018. IPEDF, 2018). Study population In 2012, a survey estimated the population at 35,520 inhabitants, of whom 50.7% were male (IPEDF, 2018). This population is marked by significant socioeconomic vulnerability, including a low average per capita income (R$573.00; approximately US$112.00), limited educational attainment (5.8% illiteracy, 38.9% with incomplete elementary education, and only 9.6% having completed elementary school), and a Human Development Index (HDI) of 0.616. Within the Federal District, the Gini coefficient is 0.553, highlighting the high level of social inequality. In terms of racial self- identification, most residents identify as mixed race (62%) or black (15%), with the remainder predominantly white (IBGE, 2018; Sellera et al., 2019). Sample Size The sample size was estimated using the formula n = [DE x Np(1 - p)]/[d 2 /Z 2 1-α /2 x (N - 1) +p x (1 - p)] in which design effect (DE) was settled as 1, expected prevalence (p) of infection as 50%, confidence limits (d) as 3%) and population size as 35,520 (IPEDF, 2018). where the design effect (DE) was set at 1, the expected prevalence (p) of infection at 50%, the confidence limit (d) at 3%, and the total population size at 35,520 (IPEDF, 2018). Based on these parameters, the minimum required sample size was calculated to be 1,060 participants. Inclusion, exclusion and case definition The study population comprised individuals of all age groups who were cognitively and physically able to respond to the interview questions. Eligibility required formal agreement to participate after clear explanation of the research objectives, procedures, and potential implications. The consent process followed ethical and legal standards: adult participants, as well as parents or legal guardians of underage or legally incapacitated individuals, signed informed consent forms authorizing participation and the collection, storage, and use of biological samples. Additionally, minors and legally incapacitated participants were asked to provide their own assent, in accordance with best ethical practices. Participants were excluded if they refused to participate in the interview, declined to provide blood samples, or withdrew consent at any point during the study process. For the purpose of epidemiological analysis, cases were defined as participants with serum samples testing positive for IgG antibodies, indicating prior exposure to the measles virus through natural infection or vaccination. Sampling Strategy We used the Federal District 2020 shapefile (https://www.geoportal.seduh.df.gov.br/geoportal/ (accessed on 3 January 2022)) to delimit the study area. Using QGIS 3.10.14 (http://www.qgis.org (accessed on 20 January 2023), we marked the urban area of SCIA-Estrutural as a polygon, excluding industrial sectors, non-residential public buildings, parks, and rural areas. Two new shapefiles were created to randomly draw eligible households: one with 1,060 points for the first sample and another with 1,060 points for a second draw. A multi-ring buffer was added with a 0.00019-degree (20.3 m) radius, and points falling outside buildings were manually adjusted to the nearest building within the buffer. Sampled points were stored in *.kml files and uploaded into Locus Map 4.5.5, an offline navigation Android application installed on tablets to guide field teams. Each team, composed of a driver, an interviewer, and a phlebotomist, visited the sampled points between 24 September and 19 December 2021, from Thursday to Sunday. All residents of SCIA-Estrutural were eligible to participate, and one resident per household was selected using a random numbers table. Points were replaced when (i) households refused participation, (ii) no building was found within the buffer, or (iii) no one was present after three consecutive visits. This spatial sampling strategy has previously been described in Nogueira de Brito et al (2023). Data Collection Primary data and biological samples were collected during household visits, after written informed consent was obtained. Standardized questionnaires were applied by trained interviewers using the REDCap 9.3.8 platform (Harris et al. 2009), hosted at the University of Brasília. Peripheral Blood samples were collected in 5mL tubes with clot activator and transported to the laboratory of the Molecular Diagnostics Hospital of the University Hospital of Brasilia (4–6 °C). Each participant received a unique serial number to link questionnaires and samples, ensuring confidentiality and anonymity. Laboratory analysis The selected participants were interviewed, and their demographic information was collected and stored in data. In the laboratory, we followed the EUROIMMUN Anti-Measles Virus IgG manufacturer’s guidelines for the indirect ELISA analysis technique, to process the biological sample. Patient sera, already diluted, were transferred to previously sensitized microplates and incubated for 30 minutes. Subsequently, an automated microplate washer was used to remove antibodies that were not bound, followed by a triple wash to ensure the complete removal of residual wash buffer. Next, a specific enzyme conjugate was transferred to the microplates and incubated. A second wash was carried out to remove the antibodies that did not bind to the second antigen. After incubation, the substrate and stop reaction were added, 30 minutes after adding the stop solution. Analysis was carried out using an ELISA reader. The following calculations were carried out: 𝐶𝑜𝑛𝑡𝑟𝑜𝑙 (𝐶𝑡𝑟) 𝑃𝑎𝑡𝑖𝑒𝑛𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 (𝑆𝑝) = 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑐𝑎𝑙𝑖𝑏𝑟𝑎𝑡𝑜𝑟 3 (𝐶𝑎𝑙𝑖 3) 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑝𝑎𝑡𝑖𝑒𝑛𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 (𝑋) (𝑋) = (𝐶𝑎𝑙𝑖 3) ∗ (𝐶𝑡𝑟) (𝑆𝑝) The results were interpreted as follows: indices less than <0.8 were negative; ≥ 0.8 <1.1 were inconclusive, and indices greater than ≥ 1.1 were positive. Statistical analysis A descriptive analysis was conducted to summarize the study population, including the distribution of frequencies, means, medians, and proportions of reported measles antibody cases. The presence of measles antibodies was further examined in relation to independent variables such as age group, sex, educational level, self-reported history of measles infection, and availability of a vaccination card. This approach enabled the identification of potential associations and patterns between sociodemographic and immunization-related factors and the seroprevalence of measles antibodies. Comparisons between groups were performed using the chi-square test, and prevalence ratios (PRs) with their respective 95% confidence intervals (CIs) were estimated. The PRs were obtained through Poisson regression models with robust variance. Variables considered significant in the analyses (p < 0.05) or based on confidence interval assessment were further evaluated graphically to assess their distribution in relation to IgG seropositivity. For continuous exposures, distributions were explored through plots, while for ordinal variables, the Cochran-Armitage test was applied to assess linear trends in proportions. All statistical analyses were performed using R software, version 4.0.0 (R Core Team, 2025). Data visualization was conducted with the ggplot2 package (Wickham, 2016). Descriptive statistics (median and interquartile range) and data manipulation were carried out using functions from the dplyr package (Wickham et al., 2023), within the tidyverse framework (Wickham et al., 2019). Prevalence ratios and 95% CIs were calculated using the epiR package (Stevenson & Sergeant, 2025), and, alternatively, regression models were fitted with the sandwich (Zeileis, 2004; Zeileis, 2006) and lmtest (Zeileis & Hothorn, 2002) packages. The Wilcoxon rank-sum test was applied to compare the distribution of age between IgG serostatus groups. Linear trend analyses for ordinal exposures were performed using the DescTools package (Signorell 2025). 1 RESULTS In total, 1,060 participants were interviewed between June 21 and November 2021 in the population living in SCIA-Estrutural. Of this total, 58 samples were excluded due to registration problems, reducing the total to 1002 people, of which 112 samples were invalid, due to low quantity or quality of the sample, thus remaining in the analysis 890 participants whose samples obtained valid results in the test for detection of IgG against the measles virus. The final sample included 890 participants, of whom 65.2% (581/890) were women. The median age was 39 years (interquartile range [IQR]: 29–49). Most participants identified themselves as Black or mixed race (74.9%, 667/890). Regarding educational attainment, 37.3% (332/890) reported being illiterate or having incomplete elementary education. More than half of the participants (57.1%, 508/890) reported a monthly household income of up to one minimum wage. The median number of cohabitants per household was 4 (IQR: 2–5). A history of measles was reported by 34.7% (309/890). Vaccination cards were presented by 28.5% (254/890), regardless of completeness, while 61.2% (545/890) self-reported having received at least one dose of measles vaccine. The overall characteristics of the study population are summarized in Table 1. Table 1 - Distribution of sociodemographic variables by measles IgG serostatus (ELISA test), SCIA-Estrutural, Brazil, from June 2021- November 2021. The overall seroprevalence was 71.1% (633/890; 95% 68.1-74.1). There’s no significant difference between seroprevalence among sex, although in age there’s a significant difference (p < 0.001). The age stratums and prevalence ratios show that there is a tendency of an increase of antibodies detection while age increases, as can be seen by the increase of the Prevalence Ratios (Table 1). The median age of participants with positive serostatus was 43 years-old (interquartile range [IQR]: 22–64), while the median age of seronegative participants was 30 years-old (interquartile range [IQR]: 14–46). The Wilcoxon rank sum test with continuity correction comparing the medians p-value was lower than 0.001. The age distribution by serostatus is presented in the figure below: Figure 1 – Age distribution according to IgG status, SCIA-Estrutural, Brazil, from June 2021- November 2021. 1 RESULTS There was no significant difference regarding serostatus in self-declared races (Table 1), although there was a difference in the educational status (p = 0.004). Observing the seroprevalence by educational level, as shown in Figure 2, we can observe that there is indeed a downward trend in IgG prevalence as education level increases. In addition to the prevalence ratio values in Table 1, this finding is also confirmed by the result of the Cochran-Armitage test, which obtained a p-value of 0.012. Figure 2 – Seroprevalence from each educational level. SCIA-Estrutural, Brazil, from June 2021- November 2021. The monthly income variable was borderline to reach statistical significance (p = 0.078) in the Table 1 analysis, with a tendency of decrease of the Prevalence Ratio while the monthly income was higher than was further confirmed with the Cochran-Armitage test (p = 0.053). The median number of cohabitants in the same residence with positive serological status was 3 (interquartile range [IQR]: 2–4), while the median from those with negative serological status was 4 (interquartile range [IQR]: 3–5) and the Wilcoxon rank sum test with continuity correction comparing the medians p-value was lower than 0.001. The number of cohabitants distribution by serostatus is presented in the figure below: Figure 3 – Number of cohabitants distribution according to IgG status, SCIA-Estrutural, Brazil, from June 2021- November 2021. The variables having a vaccination card (p = 0.024) and previous measles infection (p < 0.001) were also statistically associated in both analyses (Table 1). However, since these variables were already dichotomous and the outcome was also dichotomous, no further statistical exploration was performed. Importantly, the prevalence ratios did not cross 1, confirming the significance of the associations. 1 DISCUSSION The overall seroprevalence of IgG against Measles detected in this study 71.1% (633/890; 95% 68.1-74.1) indicates that vaccine coverage may below the recommended by the international authorities (GBD 2023). Interestingly, the seroprevalence rates are higher in older groups (Table 1 and Figure 1). This age-dependent pattern may reflect a combination of factors. The higher seroprevalence in older participants (>60 years) is likely due to natural measles infections before the widespread use of vaccination in Brazil. Middle-aged individuals (30–50 years) benefited from the consolidation of the National Immunization Program and mass immunization campaigns during the 1990s and early 2000s, which led to the interruption of endemic transmission in 2000. In contrast, the lower seroprevalence in younger age groups (<30 years) probably reflects the recent decline in vaccination coverage observed in Brazil since 2015, raising concerns about reduced population immunity and increased susceptibility to outbreaks. Therefore, the differences in median age between seropositive and seronegative groups are consistent with a mixed contribution of natural infection in the older groups and waning vaccine coverage in younger groups (Minakaua et al. 2023; Loureiro et al. 2024). In addition to the associations observed in Table 1 and confirmed by the Cochran– Armitage tests (p = 0.012 for educational level; p = 0.053 for monthly income), the literature consistently shows that lower socioeconomic status and lower educational attainment are significant predictors of vaccine hesitancy in Brazil (Brow et al. 2018; Barata et al. 2025). However, our findings indicate a different pattern: seroprevalence of IgG against measles was higher among participants with lower educational levels (77.9% among illiterate or incomplete elementary school) and decreased progressively in more educated groups (65.7% in those with college education). A similar, although borderline, trend was observed for income, with lower prevalence ratios among participants with higher earnings (p = 0.053). These results suggest that, in this population, socioeconomic variables may not operate solely through vaccine confidence or hesitancy, as frequently described, but may also reflect other factors such as differences in exposure history, access to health services, or cohort effects that were not directly assessed in our analysis. The borderline significance for income reinforces the presence of a potential social gradient in immunity, although further studies are needed to clarify the mechanisms underlying these associations. In our study, the median number of cohabitants among seronegative individuals was notably higher (median = 4; IQR: 3–5) compared to those who were seropositive (median = 3; IQR: 2–4), with this difference being highly statistically significant (Wilcoxon rank sum test, p < 0.001). This pattern suggests that individuals living in more crowded households may have different histories or transmission dynamics affecting their serological status. The literature supports the significance of household size in measles transmission: a modeling study simulating global demographic changes revealed that reductions in average household size (from approximately 7 to 4.4 persons between 1968 and 2019) contributed substantially to the decline in measles incidence, in part by reducing opportunities for transmission within households (Bidari and Yang 2024). Although our data does not directly capture transmission events, the observed negative association between the number of cohabitants and seropositivity may reflect a complex interplay of factors. Larger households could indicate lower likelihood of natural infection due to lower exposure intensity, or potentially reflect variations in vaccine access, immunity waning, or demographic characteristics not captured in this analysis. These findings invite further investigation into how household composition influences immunity and could inform targeted public health strategies in vulnerable settings. In our study, two variables showed significant associations with IgG seropositivity: possession of a vaccination card (p = 0.024) and self-reported history of previous measles infection (p < 0.001). Having a vaccination card was positively associated with seropositivity, which may reflect adherence to immunization programs and engagement with public health policies. This finding is consistent with previous studies indicating that vaccination card ownership is a reliable proxy for vaccination status and overall access to healthcare services (Danovaro-Holliday et al., 2018). As expected, reporting a previous measles infection was strongly associated with the presence of IgG antibodies. Despite potential recall bias, measles is a clinically distinct disease, often remembered due to their intense rash and pruritus, which tend to leave a lasting impression on the affected individual. Similar associations have been described in seroepidemiological surveys, where past measles infection was strongly predictive of detectable immunity (Strebel and Perry, 2024). 1.1 Limitations Although the ELISA technique used is known to have high levels of sensitivity and specificity in detecting the presence of antibodies in patients’ serum, it only detects the internal protein of the virus. This may be a limitation, as immunity to measles may involve other viral components. In addition, antibody titration was not carried out on the patients’ sera, which could provide additional information on the strength of the immune response (Godoy and Meira, 2000). The study did not detect IgM antibodies, a test that could have helped establish whether a measles infection was recent or not. Identifying recent infections is crucial as immediate measures can be taken to control them, especially given the virus’s high transmissibility and prevalence in the population. IgM detection is most effective within the initial 7 days after infection, but after this window, specifically 3 days after the onset of rashes, approximately 30% of the tests may yield false-negative results, potentially impacting result accuracy (WHO, 2025). There was a possibility of memory bias when collecting information about the participants’ history of measles. This is because people may not accurately remember past events or may provide incorrect information, which can affect the accuracy of the data collected. 1.2 Conclusions This study provides important insights into measles immunity in Brazil, revealing suboptimal seroprevalence (71.1%) and marked differences across age groups, socioeconomic strata, and household composition. The lower immunity among younger adults is particularly concerning, as it reflects declining vaccine coverage in recent years and underscores the urgent need to strengthen immunization programs to prevent future outbreaks. Unexpectedly, higher seroprevalence among participants with lower education and income levels suggests that immunity in this population may be shaped by complex interactions between historical exposure, vaccination practices, and social determinants of health. Furthermore, the inverse association between household size and seropositivity highlights the potential role of demographic factors in shaping measles transmission dynamics. Taken together, these findings emphasize the need for targeted strategies to increase vaccine uptake, improve health system outreach, and monitor immunity gaps, particularly among younger and socioeconomically diverse populations. Addressing these gaps will be essential to sustaining measles elimination goals and ensuring equitable protection across all segments of the population. 1.3 Acknowledgements The authors thank the Laboratory of Molecular Diagnosis (LDM) at Hospital Universitário de Brasília (HUB) technical staff for providing technical support in executing CMIA tests, especially Luciano Nonato Martins and Daiani Haddad. They also thank the administration of the city of Estrutural for their support in the fieldwork 1.4 Funding Elza Ferreira Noronha, Gustavo Adolfo Sierra Romero, Rodrigo Haddad, and Wildo Navegantes de Araújo acknowledge the Ministério da Educação (MEC) for the support in the COVID19 response by the University of Brasília (#23106.028855/2020-74). Walter Massa Ramalho, Wildo Navegantes de Araújo, and Rodrigo Haddad acknowledge the Fundação de Amparo à Pesquisa do Distrito Federal (FAP-DF) for grants that supported this research (#00193-00000495/2020-72) 1.5 Ethics and declarations This study received approval from the research ethics committee: CEP-FM/UnB, under registration numbers CAAE 39892420.7.1001.5558 and CAAE 40557020.6.3001.5553. Participants’ data were treated with confidentiality, with no sharing or disclosure to third parties. This research adhered to the Resolution no. 466, of the National Health Council of Brazil Plenary, which outlines the ethical and scientific principles governing research involving human subjects. 1.6 Competing interests The authors affirm that they do not have any conflicts of interest to disclose. 1.7 Supplementary information None References Barata RB, França AP, Guibu IA, et al. Vaccine hesitancy and consequences for vaccination coverage in children at 24 months of age, born in 2017-2018, living in the state capitals, Federal District and 12 inner region cities of Brazil. Epidemiol Serv Saude. 2025;33(spe2):e20231097. doi:10.1590/S2237- 96222024v33e20231097.especial2.en Bidari S, Yang W. The impact of household size on measles transmission: A long-term perspective. Epidemics. 2024;49:100791. doi:10.1016/j.epidem.2024.100791 Boadle A. Brasilia closes Latin America’s largest rubbish dump. Reuters. 2018 Jan 20 [cited 2025 Aug 27]. 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Table 1 - Distribution of sociodemographic variables by measles IgG serostatus (ELISA test) and bivariate analysis with Prevalence Ratios, SCIA- Estrutural, Brazil, from June 2021- November 2021. 1 DISCUSSION (n = 890) Sex Male (n = 309) 216 (69.9%) 93 (30.1%) 0.94 (0.76 -1.16) 0.558 Female (n = 581) 417 (71.8%) 164 (28.3%) - Age (Years) 1-10 (n = 7) 6 (85.7%) 1 (14.3%) - < 0.001 11-20 (n = 77) 50 (64.9%) 27 (45.1%) 0.75(0.53-1.06) 21-30 (n = 195) 92 (47.2%) 103 (52.8%) 0.70(0.39-0.77) 31-40 (n = 202) 137 (67.8%) 65 (32.2%) 0.79(0.57-1.08) 41-50 (n = 202) 161 (79.7%) 41 (20.3%) 0.93(0.62-1.26) 51-60 (n = 120) 106 (88.3%) 14 (11.7%) 1.03 (0.75-1.40) 61-64 (n = 32) 30 (93.8%) 2 (6.2%) 1.09 (0.79-1.49) ≥65 (n = 49) 45 (91.8%) 4 (8.2%) 1.07(0.78-1.46) Self-Declared Race White (n = 144) 99 (68.7%) 45 (31.3%) - 0.725 Black or mixed race (n = 667) 474 (71.1%) 193 (28.9%) 1.03(0.83-1.28) Other races (n = 32) 24 (75.0%) 8 (25.0%) 1.09 (0.69-1.70) Education Illiterate or incomplete Elementary school (n = 332) 259 (40.9%) 73 (28.8%) - 0.004 Elementary school (n = 160) 107 (16.9%) 53 (20.6%) 0.86(0.76-0.97) High school (n = 316) 210 (33.2%) 106 (41.2%) 0.85(0.77-0.93) College (n = 70) 46 (7.6%) 24 (9.3%) 0.84 (0.70-1.00) Monthly income 2–3 minimum wages (=290) 194 (66.9%) 96 (33.1%) 1.02(0.81-1.29) ≥4minimum wages (= 43) 28 (65.1%) 15 (34.9%) - Number of cohabitants 1–2 (= 225) 182 (80.8%) 54 (19.2%) - 0.031 3–4 (= 418) 295 (70.5%) 123 (29.5%) 0.91 (0.76-1.10) 5–6 (=177) 118 (66.6%) 59 (33.4%) 0.86 (0.68-1.08) ≥ 7(= 53) 32 (60.4%) 21 (39,4%) 0.78 (0.52-1.12) Have Measles before? Yes (n = 309) 248 (80.2%) 61 (19.8%) 1.25 (1.03-1.51) >0.001 No (n = 318) 204 (64.1%) 114 (35.5%) - Have vaccination card? Yes (n = 254) 195 (76.7%) 59 (23.3%) 1.13(0.93-1.39) 0.024 No (n =255) 172 (67.4%) 83 (32.6%) - Was vaccinated against Measles before? Yes (n = 545) 379 (69.5%) 166 (30.5%) 0.86(0.74-0.99) 0.142 No (n = 52) 42 (80.7%) 10 (19.3%) - Information & Authors Information Version history V1 Version 1 17 October 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords antibody susceptibility disease control epidemiology evolution immune responses infection measles virus reinfection vaccines/vaccine strains virus classification Authors Affiliations Janet Sallis Nimoh Mensah 0000-0003-2111-1714 Universidade de Brasilia View all articles by this author Ana Izabel Passarella Texeira Universidade de Brasilia View all articles by this author Carolina Carvalho Gontijo Universidade de Brasilia View all articles by this author Walter Massa Ramalho Universidade de Brasilia View all articles by this author Rafael da Silva Faria [email protected] Universidade de Brasilia View all articles by this author Rodrigo Haddad 0000-0003-4699-164X Universidade de Brasilia View all articles by this author Wildo Navegantes de Araújo Universidade de Brasilia View all articles by this author Metrics & Citations Metrics Article Usage 196 views 149 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Janet Sallis Nimoh Mensah, Ana Izabel Passarella Texeira, Carolina Carvalho Gontijo, et al. 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