Maternal Vaccination against COVID-19, Influenza, Pertussis, and Respiratory Syncytial Virus: A Scoping Review

Maternal Vaccination against COVID-19, Influenza, Pertussis, and Respiratory Syncytial Virus: A Scoping Review | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Maternal Vaccination against COVID-19, Influenza, Pertussis, and Respiratory Syncytial Virus: A Scoping Review Isolde Sommer, Andreea Dobrescu, Larisa Pinte, Camilla Neubauer-Bruckner, and 24 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9013883/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 14 You are reading this latest preprint version Abstract Pregnancy and early infancy are periods of heightened vulnerability, with SARS-CoV-2 and influenza infections linked to adverse pregnancy outcomes, including preterm birth, and stillbirth. Maternal vaccination provides direct protection to mothers by active immunisation and to infants by passive immunisation. This scoping review mapped and described published literature on maternal vaccination against COVID-19, influenza, pertussis, and RSV, including which outcome domains were studied and the timing of vaccination examined, with the aim of identifying evidence gaps and supporting decision-makers in choosing priority areas for subsequent systematic review topics. A comprehensive literature search across multiple databases of studies published from January 2000 to October 2025 identified 636 publications (541 primary studies, 95 evidence syntheses). Studies on COVID-19 (261 studies, 45 reviews), influenza (161 studies, 29 reviews), pertussis (113 studies, 20 reviews), and RSV (20 studies, 11 reviews) were analysed. Substantial evidence on COVID-19, influenza, and pertussis vaccination on efficacy, effectiveness, safety and immunogenicity outcomes and the optimal timing of vaccination in relation to these outcomes during pregnancy is available. RSV vaccination evidence is limited. Updated systematic reviews would be helpful to clarify the optimal timing of COVID-19 vaccination and the effectiveness and safety of the coadministration of influenza and pertussis vaccines. Health sciences/Diseases Health sciences/Health care Biological sciences/Immunology Health sciences/Medical research Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Pregnancy and early infancy are periods of increased vulnerability to infection, which can lead to severe complications for the mother, foetus, or young infant. Infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or seasonal influenza virus have been shown to increase the risk of adverse pregnancy outcomes such as preterm birth, or stillbirth 1 , 2 . Newborns and young infants are also at significant risk of severe, potentially fatal complications after infections with Bordetella pertussis or Respiratory Syncytial Virus (RSV) 3 , 4 . As of April 2024, increasing pertussis cases were being reported in the European Union and the European Economic Area (EU/EEA), with the highest burden in infants < 1 year of age in the majority of EU/EEA countries, indicating the importance of significantly strengthening maternal vaccination approaches 5 . RSV accounted for 1.4 million hospital admissions and 45,700 deaths globally in infants aged 0–6 months in 2019 6 . In the European Union (EU), RSV was estimated to affect 72 out of 1000 infants under the age of two months and affecting especially children under the age of 5 7 . Due to the functional immaturity, the newborn’s immune system characteristically lacks reactivity to multiple microorganisms to prevent excessive inflammatory responses 8 . Newborns and young infants can be protected from serious infections by the transplacental transfer of antibodies and other mediators of immunity from their mothers during pregnancy and through maternal antibodies transferred to the child through breastfeeding 9 . Vaccination during pregnancy boosts maternal levels of pathogen-specific antibodies, providing protection to both mother and infant during the first months of life 10 . Many EU countries have introduced national vaccination programmes designed for pregnant women, with some differences in the recommended gestational timing of vaccination and the choice of vaccines 11 . Mapping the maternal vaccination literature is a first step to understanding potential evidence gaps, any significant updates to the literature or new evidence on this topic. The aim of this scoping review was to identify evidence gaps and support decision-makers in choosing priority areas for subsequent evidence synthesis by identifying and mapping the existing research landscape of the efficacy, effectiveness, safety and immunogenicity of maternal vaccination against COVID-19, influenza, pertussis, and RSV, including available literature examining these outcomes in relation to the optimal timing for administration of these vaccinations during pregnancy. Optimal timing is the vaccination window in pregnancy that provides the greatest effectiveness, antibody transfer, and safety for mother and infant. This review did not aim to appraise study quality, estimate pooled effects, or judge benefits or safety. Results Our literature searches across various databases and registries identified 6,523 records after removal of duplicates. After screening titles and abstracts, 5,411 records were deemed irrelevant and excluded. We identified one record via citation searching. We then conducted a full-text review of 1,102 records, leading to the exclusion of 466 records based on a detailed assessment. Ultimately, our review incorporated 636 publications (637 records): 541 primary studies and 95 evidence syntheses. The study selection process is visually summarised in Figure 1. Supplementary information 1 lists the studies excluded by full-text assessment, with the corresponding reasons for exclusion. Figure 1: PRISMA flow diagram illustrating the study selection process* *adapted from Page et al. 12 Abbreviation: n = number of records COVID-19 We identified 261 primary studies (2 RCTs, 225 controlled cohort studies, 17 case-control studies, 5 test-negative design studies, and 12 cross-sectional studies) and 45 evidence syntheses (41 systematic reviews, 2 rapid reviews, and 2 scoping reviews) addressing the effectiveness, safety, and/or immunogenicity of COVID-19 vaccination in pregnant participants. The optimal timing of maternal COVID-19 vaccination in relation to the outcomes including immunogenicity, clinical outcomes and/or safety, was examined in 101 of these publications. Supplementary information 2 lists the included studies for maternal COVID-19 vaccination. Five primary studies and one evidence synthesis were available as preprints only. Seven studies are ongoing, or the results have not been published yet (see Supplementary information 3). Most studies compared maternal COVID-19 vaccination against no vaccination (191 primary studies and 38 evidence syntheses). One study compared COVID-vaccination with influenza vaccination. Eighty-six studies evaluated a different number of doses of maternal COVID-19 vaccination, 39 analysed different types of COVID-19 vaccines, and 11 evidence syntheses examined either different dosages, types of vaccines, or both. Thirty- seven studies compared maternal COVID-19 vaccination with maternal SARS-CoV-2 infection. Eighty-three publications (64 primary studies and 19 evidence syntheses) reported on maternal effectiveness outcomes. Infant effectiveness outcomes were reported in 31 publications. Maternal safety outcomes were reported in 148 publications, while infant safety outcomes were reported in 174 publications. Ninety-three publications reported maternal immunogenicity data, and 80 publications reported infant immunogenicity outcomes. Figure 2 and Supplementary information 4 display all studies and systematic reviews that were identified for maternal COVID-19 vaccination. Figure 2: Evidence map for maternal COVID-19 vaccinations *Different types of vaccines, and different numbers of doses Numbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, yellow cohort studies, red cross-sectional studies, brown evidence synthesis, and grey test-negative design studies. Abbreviations: COVID-19 = Coronavirus disease of 2019; vs = versus Four systematic reviews on maternal COVID-19 vaccination were published in 2024 13-16 . They compared different types of COVID-19 vaccines (Astra Zeneca, BioNTech/Pfizer, Janssen, Moderna, Sinovac, Sinopharm, Covaxin; Johnson & Johnson) against no vaccination, as well as the timing 13,15 , vaccine types 15,16 and total number of administered doses of COVID-19 vaccines during pregnancy 14-16 . Fernández-García et al. 14 analysed 24 studies with 730,269 participants, Ciapponi et al. 16 137 studies with 638,791 participants, Wang et al. 13 39 studies with more than 1,600,000 participants, and Lei et al. 15 82 studies with 3,676,654 participants. All studies included in the reviews are observational studies. The authors reviewed mRNA, viral vector, and inactivated vaccines administered during various trimesters (1-3 doses). While the systematic reviews by Fernández-García et al. 14 , Ciapponi et al. 16 and Lei et al. 15 focused on the efficacy/effectiveness and safety outcomes for both mother (including/comprising infection, severe COVID-19 disease, hospital admission, death, miscarriage, caesarean section, postpartum haemorrhage, gestational diabetes, hypertensive disorders of pregnancy, and any other adverse events) and infant (including congenital malformation, infection, stillbirth, preterm birth, admission to neonatal intensive care unit, small for gestational age, and neonatal death), Wang et al. 13 included only safety outcomes for the mother (including miscarriage, caesarean delivery, emergency caesarean delivery, very preterm birth (<32 weeks), preterm birth (<37 weeks), spontaneous preterm birth, medically indicated preterm birth, placental abruption, postpartum haemorrhage, and preeclampsia) and infant (including stillbirth, meconium-stained amniotic fluid, small for gestational age, 5-min Apgar scores of less than 7, low birth weight (<2500 g), very low birth weight (<1500g), neonatal intensive care unit admission, and respiratory complications). Supplementary Information 5 displays the study and population characteristics of the selected systematic reviews, and Supplementary Information 6 displays the reported outcomes. Influenza In total, 190 publications were included, comprising 161 primary studies (14 RCTs, 117 cohort studies, 20 case-control studies, five cross-sectional studies, five test-negative design studies) and twenty-nine systematic reviews; Supplementary information 7). One study was published as a preprint. We identified six ongoing studies, or the results have not been published yet (Supplementary information 3). Of the 190 publications, 167 compared vaccination against no vaccination (140 primary studies and 27 systematic reviews). Among these, there were seven placebo-controlled RCTs and six systematic reviews, including placebo-controlled studies. Additionally, 21 studies and three systematic reviews compared one vaccine with another vaccine or vaccine type. The timing of vaccination was investigated in nine case-control studies, 57 cohort studies, one cross-sectional study, two RCTs, two test-negative design study and in eight systematic reviews. Maternal efficacy/effectiveness outcomes were reported in 41 publications. Forty-eight publications reported infant efficacy/effectiveness outcomes. Eighty-three publications addressed maternal safety outcomes, and 135 reported infant safety outcomes. Additionally, 25 publications provided data on maternal immunogenicity, while 22 reported infant immunogenicity outcomes. Figure 3 and Supplementary information 8 display all studies and systematic reviews that were identified for maternal influenza vaccination. Figure 3: Evidence map for influenza vaccinations *Other vaccines Numbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, yellow cohort studies, red cross-sectional studies, brown systematic reviews, and grey test-negative design studies. Abbreviation: vs = versus The two most recent systematic reviews on influenza vaccination during pregnancy were published in 2023 17 and 2021 18 . The systematic review by Bansal et al. 18 included fourteen studies involving over 53,000 healthy pregnant participants who received trivalent inactivated seasonal influenza vaccine, another commercially available influenza vaccine, pneumococcal vaccine, meningococcal vaccine, placebo, or no vaccination. Wolfe et al. 17 examined 63 observational studies with over 943,598 participants, including several comparisons but focusing their primary analysis on trivalent or quadrivalent seasonal influenza vaccines against no vaccination in pregnant women. Bansal et al. 18 assessed the optimal timing of vaccination uptake for vaccine effectiveness across all trimesters. The maternal outcomes of interest included vaccine efficacy in preventing infection and hospitalisation rates due to severe influenza, rates of febrile illnesses, immunogenicity, and adverse events. In infants, outcomes focused on vaccine efficacy in providing protection against influenza, hospitalisation rates due to influenza infection, the rate of febrile illnesses, the risk of low birth weight and preterm birth, and immunogenicity. The focus of Wolfe et al. 17 was on maternal safety outcomes, such as non-obstetric serious adverse events, and infant safety outcomes like spontaneous abortion, stillbirth, preterm birth, small-for-gestational-age birth, low birth weight, and congenital anomalies. Further details about characteristics and outcomes reported by the two systematic reviews are provided in Supplementary information 5 and 6. Pertussis We identified 113 primary studies and 20 systematic reviews addressing the efficacy/effectiveness, safety, and/or immunogenicity of pertussis vaccination in pregnant participants (Supplementary information 9). Of the 113 primary studies, 17 were RCTs, 73 were controlled cohort studies, one was a test-negative design study, three were cross-sectional studies, and 19 were case-control studies. Five studies were ongoing, and the results were not yet published at the time of analysis (Supplementary information 3). Ninety-five studies compared maternal pertussis vaccination against no vaccination, four of them compared vaccination against a placebo. Nine studies compared pertussis vaccination against other vaccines or vaccine types. Fifteen systematic reviews compared vaccination against placebo/no vaccination, and three against placebo/other vaccines. Infant efficacy/effectiveness was reported in 43 publications. Safety outcomes were reported in 73 publications for mother and/or infant. Thirty-seven publications reported maternal immunogenicity outcomes. Infant immunogenicity outcomes were reported by 59 publications. The timing of vaccination on the different outcomes was evaluated in 49 publications. Figure 4 and Supplementary information 10 display all studies and systematic reviews we identified for maternal pertussis vaccination. Figure 4: Evidence map for pertussis vaccinations *Different type of vaccines, and different number of doses Numbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, yellow cohort studies, red cross-sectional studies, brown systematic review, and grey test-negative design studies. Abbreviation: vs = versus Six systematic reviews examining maternal pertussis were published between 2021 and 2025 19-24 . The reviews compared maternal pertussis vaccination against no vaccination, standard or other vaccines 19-23 , and four reviews also compared against placebo 19,21-23 . One review compared different timepoints of maternal vaccination 24 , two reviews provided subgroup analysis on timing 19,23 . Nguyen et al. 20 included 26 studies (RCTs, cohort studies, case-control studies, and case series) with more than 350,000 pregnant participants and their offspring, Gidengil et al. 19,25 included four RCTs, thirteen cohort studies, and one case-control study covering 1,932,709 pregnant women with vaccination between 28 to 32 gestational weeks, Andersen et al. 21 included 19 studies (six RCTS and 13 cohort studies) with 1,749,463 pregnant women, and Simayi et al. 2022 22 included 6 RCTs with overall 1,400 women with uncomplicated singleton pregnancies with vaccination between 18 to 36 gestational weeks, Shi et al. 23 included 7 RCTs and 10 case-control studies with 3,704 pregnant women, and de Weerdt 24 included 35 studies (4 RCTS and 31 observational studies) with 416,278 pregnant women. The systematic reviews by Gidengil et al 19 , Nuygen et al. 20 , and Shi et al. 23 assessed the vaccines Adacel ® (Sanofi) or Boostrix ® (GlaxoSmithKline), while the others did not report the type of vaccines that were used in the studies. Two systematic reviews focused on maternal safety outcomes (including non-pertussis infection, spontaneous abortion, chorioamnionitis, death, autoimmune disease, cardiovascular events, diabetes, eclampsia/preeclampsia, encephalitis/encephalopathy, Guillain-Barré syndrome, preterm labour, reproductive system events, seizures, and other adverse events (1 cohort study)) and infant safety outcomes (including non-pertussis infections, neonatal death, stillbirth, autism or attention deficit hyperactivity disorder (ADHD) in infants, birth defects, cardiovascular events, death in infants, encephalitis/encephalopathy, intussusception, meningitis, seizure, stroke, low birthweight, preterm birth, small or large for gestational age, respiratory distress syndrome, transient tachypnea of newborn, tachycardia or bradycardia, hemolytic disease, neonatal jaundice, anaemia, syndrome of infant of mother with gestational diabetes, and hypoglycaemia) 19,21 . One systematic review focused on maternal and infant safety (severe adverse events) and infant immunogenicity (pertussis IgG) 22 , three addressed infant efficacy/effectiveness (incidence of pertussis), maternal and infant safety outcomes (severe adverse events), and infant immunogenicity (pertussis IgG) 20,23,24 . The review by De Weerdt et al. 24 additionally provided information on maternal immunogenicity outcomes. Supplementary information 5 displays the study and population characteristics of these systematic reviews, and Supplementary information 6 displays reported outcomes. Respiratory syncytial virus (RSV) We identified 20 primary studies and 11 evidence syntheses addressing the efficacy, effectiveness, safety, and/or immunogenicity of vaccination against RSV in pregnant women (Supplementary information 11). Eleven of the primary studies were RCTs, two controlled cohort studies, three were case-control studies, three were test-negative design studies, and one was a cross-sectional study. We identified 11 ongoing studies and one preprint at the time of analysis (Supplementary information 3). All RCTs compared maternal RSV vaccination against placebo, most observational studies against no vaccination, and all evidence syntheses against no vaccination or placebo. Three RCTs reported on maternal efficacy outcomes. Infant efficacy from RSV infection or RSV-associated hospitalisation was reported in 13 studies and seven systematic reviews. Safety outcomes for mother and/or infant were reported in 14 studies and 11 evidence syntheses. Nine studies and three systematic reviews examined maternal and infant immunogenicity outcomes. Infant immunogenicity was the only outcome assessed by one case-control study. The optimal timing of RSV vaccination during pregnancy was investigated in three studies. Figure 5 and Supplementary information 12 display all studies and systematic reviews we identified for maternal RSV vaccination. Figure 5: Evidence map for RSV vaccinations *Other vaccine Numbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, and brown systematic reviews . Abbreviations: RSV = Respiratory syncytial virus; vs = versus The systematic reviews by Mapindra et al. 26 , Phijffer et al. 2024 27 , and Alandijany et al. 2025 28 provide the most recent and comprehensive systematic reviews we identified. Mapindra et al. 26 and Phijffer et al. 2024 27 both included six RCTs comparing RSV vaccination versus placebo, with five RCTs overlapping between the reviews. Alandijany et al. 2025 28 included three RCTs and two observational studies comparing RSV vaccination against placebo or active control. Mapindra et al. 26 examined 12,734 uncomplicated singleton pregnancies, Phijffer et al. 2024 27 included 17,991 participants, and Alandijany et al. 2025 28 included 19,400 pregnant women. They received a single dose (50, 60, 120, or 240 μg) of the adjuvanted (Wyeth Lederle, NovaVax, Pfizer) or unadjuvanted RSV vaccine (GlaxoSmithKline, Pfizer). The systematic reviews by Mapindra et al. 26 and Alandijany et al. 2025 28 assessed RSV infection and RSV-related hospitalisations in infants, maternal safety, and maternal and infant immunogenicity outcomes, while the systematic review by Phijffer et al. 2024 27 reported infant RSV hospitalisation, and maternal and infant safety outcomes. Supplementary information 5 displays the study and population characteristics of these systematic reviews, and Supplementary information 6 displays reported outcomes. Discussion This scoping review mapped the evidence based on 541 primary studies and 95 evidence syntheses addressing the efficacy, effectiveness, safety, and immunogenicity of maternal COVID-19, influenza, pertussis, and RSV vaccinations. Per‑vaccine counts are not mutually exclusive because some evidence syntheses include multiple pathogens. The largest evidence base exists for maternal COVID-19 vaccination, followed by maternal influenza, pertussis, and RSV vaccination. Optimal timing of vaccination during pregnancy was investigated in 226 studies (101 COVID-19, 79 influenza, 49 pertussis, three RSV), with 29 studies (seven COVID-19, six influenza, five pertussis, 11 RSV) still ongoing or awaiting publication at the time of analysis. The evidence for maternal COVID-19 vaccination relies primarily on observational studies comparing vaccination against no vaccination. Most of these studies assessed maternal efficacy and effectiveness, as well as maternal and infant safety outcomes. Four up-to-date systematic reviews compare different commercially available COVID-19 vaccines to no vaccination before and/or during pregnancy. They cover a broad range of maternal and infant efficacy/effectiveness outcomes, as well as safety outcomes for both mother and infant. Two reviews also include outcome comparisons across different trimesters of pregnancy. Interpretation of observational signals in pregnancy requires caution. Healthy-vaccinee effects, gestational–age–dependent vaccine uptake, and time-varying confounding can bias associations toward a benefit of vaccination. Bias can also arise if exposure is defined after an outcome‑free interval. Misclassification of exposure timing or obstetric outcomes, and incomplete adjustment for parity, comorbidity, and socioeconomic status, further limit causal inference. These considerations support prioritising well‑adjusted designs and, where feasible, randomised or quasi‑experimental evidence. In contrast to maternal COVID-19 vaccination, we identified 14 placebo-controlled and comparative effectiveness RCTs for maternal influenza vaccination that report on maternal and infant efficacy/effectiveness and safety outcomes. However, most studies are observational studies, reporting safety outcomes in infants and pregnant women as well as maternal and infant efficacy/effectiveness. The most recent systematic reviews cover search periods until May or June 2021, but 44 primary studies have been published since 2021. The timing of maternal influenza vaccinations is not studied in the selected reviews. However, eight older systematic reviews and 71 primary studies are available on timing. The evidence for maternal pertussis vaccination rests on 17 placebo-controlled, no-vaccination, and comparative effectiveness RCTs. The RCTs focus on safety and immunogenicity outcomes. A large body of observational studies also reported efficacy/effectiveness outcomes. The most recent systematic review covers the search period up to February 2025. One systematic review published in 2024 specifically focuses on the timing of pertussis vaccination, one systematic review on this topic is registered 29 . We identified 20 studies on maternal RSV vaccination, 11 of which were RCTs. They report efficacy/effectiveness outcomes for infants, and safety and immunogenicity outcomes for both infants and mothers. Three studies on the timing of RSV vaccination during pregnancy are available. The most recent systematic reviews cover until 2023 and 2025 with two focusing on evidence from RCTs. This scoping review offers an overview of the current evidence for maternal COVID-19, influenza, and pertussis vaccinations. The evidence gap maps show, at a high abstract level, that existing studies cover maternal and infant efficacy/effectiveness, safety, and immunogenicity outcomes. We did not appraise risk of bias, estimate pooled effects, or draw conclusions about clinical effectiveness. Interpretation of the observational literature is limited by confounding and design issues; addressing those questions requires a focused systematic review with appropriate critical appraisal and, where possible, meta‑analysis. The evidence for optimal timing of COVID-19, influenza, and pertussis vaccination during pregnancy also appears exhaustive but the evidence is often derived from subgroup analyses. In contrast, the body of evidence for maternal RSV vaccination is relatively sparse but given its only recent approval in August 2023 by the EMA 30 and FDA 31 not surprising. Although some RCTs focus on infant efficacy, maternal and infant safety, and immunogenicity, there is a clear need for more observational studies and research on the optimal timing of RSV vaccination during pregnancy. The review also points out that, while recent systematic reviews are available for maternal COVID-19, influenza, and pertussis vaccinations, the publication of numerous new primary studies about RSV vaccinations since the last search date calls for updated reviews. For RSV vaccination, although recent systematic reviews exist, the rapid pace of ongoing research in this area suggests that more studies are likely to be published soon, necessitating continuous updates to the evidence base. Finally, the quality of these systematic reviews remains to be assessed, emphasising the importance of ensuring that the evidence they provide is both reliable and comprehensive for guiding maternal vaccination practices. This review has several limitations. First, although we developed and uploaded a protocol for this review on the Open Science Framework (https://osf.io/v3rgt/), we had to make some amendments throughout the review process to tackle the large volume of evidence. Thus, we could not do as detailed a data extraction for all studies as originally planned. With the two-staged approach to data extraction with a focus on recent and comprehensive systematic reviews, we relied on data provided by these reviews, which sometimes lacked information on dose, vaccine types, or patient characteristics. Second, another adaptation we made to the protocol was that we did not include and extract data on ongoing clinical trials. Clinical trial registrations provide useful information for characterising the research dynamic and activity in a particular field. We listed the identified clinical trial registrations in Supplementary information 3 but officially excluded them from the list of included studies to reduce the scope of this review. Despite these amendments, we believe that our approach supports decision-makers in choosing a subsequent systematic review topic. Third, because we received a large volume of evidence through database searches, we did not conduct further supplementary searches, including reference list checking, forward citation tracking, and searching the websites of regulatory agencies. It is, therefore, possible that we missed some studies that met our inclusion criteria. Finally, we excluded studies that provided only subgroup analyses of pregnant women, as their inclusion would have necessitated an excessively broad search strategy encompassing all studies involving individuals receiving vaccination against COVID-19, influenza, pertussis, and RSV. Conclusion The aim of this scoping review was to identify evidence gaps in maternal vaccination research and highlight priority areas for future evidence synthesis by systematically mapping the existing literature regarding study design, comparisons, outcomes, and timing of vaccination of both primary studies and systematic reviews. This scoping review does not address the outcome estimates of immunogenicity, efficacy, effectiveness and/or safety of COVID-19, influenza, pertussis, or RSV vaccination given during pregnancy. The unexpectedly large number of studies we identified highlights the need to focus and prioritise the scope of a subsequent systematic review to a manageable level. This can be achieved by narrowing the study designs, comparators, and outcomes, with an emphasis on identifying the most useful and specific evidence relevant to decision-making. Although there is limited evidence for specific outcomes, the availability of sufficient studies on maternal and infant efficacy/effectiveness outcomes across all four types of vaccinations indicates that reliance on immunogenicity data may not be necessary nor desirable. A further challenge for a subsequent review is the dynamic nature of this research field. This is particularly relevant for RSV vaccination, as the RSV vaccine ABRYSVO was approved by the EMA and FDA in 2023 30,31 . We identified several ongoing studies for the other three maternal vaccinations available for COVID-19, influenza and pertussis. Given the volume of efficacy, effectiveness and safety data, a follow‑on systematic review can prioritise outcome‑specific questions, for example, trimester‑specific risks of preterm birth, stillbirth, and severe maternal disease. We recommend two syntheses: timing of COVID‑19 booster vaccination during pregnancy and effectiveness and safety of coadministration of influenza and pertussis vaccines. Methods We conducted this scoping review following the Joanna Briggs Institute (JBI) Manual for Evidence Synthesis , Chapter 11: Scoping reviews 32,33 . Consistent with scoping methodology, we mapped and described evidence characteristics and outcome domains; we did not synthesise effect estimates, appraise study quality, or make judgments about efficacy, effectiveness, or safety. When reporting the results, we consulted the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) Extension for Scoping Reviews (PRISMA-ScR) 34 (Supplementary information 13). The review protocol was registered with the Open Science Framework (https://osf.io/v3rgt/). Eligibility criteria We included studies assessing the efficacy/effectiveness, safety, and immunogenicity of maternal vaccination against COVID-19, influenza, pertussis, and RSV in pregnant women irrespective of their health status. Studies had to use whole pathogen vaccines (inactivated), component vaccines (based on recombinant protein subunits or other immunogenic components of pathogens, conjugated vaccines) and vector-based vaccines. Although initially intended to include, we formally excluded clinical trial registrations but provided a list in Supplementary information 3 due to the large number of studies we identified. Table 1 presents the inclusion and exclusion criteria in detail. Table 1: Inclusion and exclusion criteria Include Exclude Population Pregnant people (any pregnancy trimester) 1 Non-pregnant people, mothers in postpartum period, breastfeeding mothers Intervention KQ1: Inactivated vaccination against COVID-19, influenza, pertussis (as combination vaccine, e.g. DTaP, Tdap, Tdap-IPV), RSV Any type of vaccine (i.e., valency), any dose, any combination KQ1a: timing of vaccination (e.g., different trimesters) Any other vaccine not mentioned (only if included in combination vaccine e.g. diphtheria and tetanus in diphtheria–pertussis–tetanus vaccine) Context Middle- and high-income countries according to the World Bank classification 2 Low-income countries according to the World Bank classification 1 Outcomes Any maternal, neonatal (preterm and term) or infant outcome (short- and long-term): efficacy and/or effectiveness outcome (e.g., infection rate, severe infection rate, mortality due to infection); safety outcome (e.g., preterm birth incidence, low birthweight, miscarriage, stillbirth, congenital abnormalities, solicited and unsolicited overall adverse events, specific adverse events, serious adverse events); and immunogenicity outcomes (e.g., geometric mean ratio) No restrictions Study designs RCTs Controlled clinical trials Non-randomised studies of interventions (controlled cohort studies, case-control studies, including test-negative design studies, controlled cross-sectional studies with a retrospective assessment of vaccination status) Rapid/Living/Scoping/Systematic Reviews Any other study design Document types Published articles Preprints Posters, conference abstracts, study protocols, books or book chapters, editorials, clinical trial registrations Date 2000 onwards Before 2000 Language No restrictions Abbreviations: COVID-19=Coronavirus disease of 2019; DTaP=Diphtheria, tetanus, and pertussis Tdap=Tetanus, Diphtheria, and Pertussis; TdapIPV=Diphtheria, tetanus, pertussis and poliomyelitis; KQ=Key question; RCTs= Randomised controlled trials; RSV=Respiratory syncytial virus; 1 Excluding studies providing only subgroup analyses of pregnant individuals ²https://datahelpdesk.worldbank.org/knowledgebase/articles/906519-world-bank-country-and-lending-groups Literature searches An expert information specialist (IK) searched for studies in MEDLINE (via Ovid), Cochrane/CENTRAL and Cochrane Database of Systematic Reviews (CDSR) (via Cochrane Library/Wiley), Embase (via Embase.com/Elsevier), COVID-19 L*OVE (app.iloveevidence.com/loves/5e6fdb9669c00e4ac072701d), Epistemonikos (epistemonikos.org), and the International HTA Database (database.inahta.org) published between 2000 to 15 April 2024. We limited our search to those published in the year 2000 and onwards to capture studies on influenza or pertussis vaccines relevant to today. We did not apply any language restrictions. The search strategies were peer-reviewed by a second information specialist, following the recommendations of Peer Review of Electronic Search Strategies (PRESS) 35 . For each database, the date of the search, the search strategy, and the number of search results were documented (see Supplementary information 14). We also searched for completed but unpublished or ongoing studies in ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (ICTRP). We checked whether publications were available for eligible studies registered in ClinicalTrials.gov or ICTRP. To identify relevant preprints, we searched Europe PMC in addition to Embase (via Embase.com/Elsevier) for studies published from 2000 to 15 April 2024. We updated all database searches in October 2025 (searches until 28 October 2025). We did not conduct supplementary searches (reference list checking or forward citation searching) due to the large number of records identified from database searches. Study selection and management Two reviewers independently screened the titles, abstracts, and relevant full-text articles against the predefined eligibility criteria using DistillerSR 36 (Evidence Partners, Ottawa, Canada). Conflicts were resolved by discussion or by consulting a third reviewer. The title and abstract screenings were piloted on a random subset of 50 search results. Full-text screening was piloted on four included studies. All results were tracked in an EndNote® 20 (Clarivate) software. Data extraction Due to the large number of included studies, we performed a two-stage approach to data extraction. First, we extracted basic information from all included studies including study information, design, intervention, comparison, and outcomes. We defined each outcome category (maternal and infant efficacy/effectiveness, safety, immunogenicity) á priori (Supplementary Information 15: Categorisation of outcomes). Second, we selected systematic reviews for each condition (COVID-19, influenza, pertussis, RSV) based on recency and comprehensiveness (i.e. number of outcomes covered). We documented reasons for not considering systematic reviews (Supplementary information 16). From selected systematic reviews, we extracted review characteristics (first author and publication year, search period, number and study design of included studies, funding sources, countries of included studies), participant characteristics (ethnicity, pregnancy week), intervention (type of vaccine, dosage), comparator (no intervention, placebo, other vaccines including type and dosage), timing of vaccination, and reported outcomes into standardised tables. One reviewer (AD, CNB, LA, CC, or LP) performed the data extraction, with a second reviewer (AD, CNB, LA, CC, or LP) checking all data extractions for completeness and accuracy. Data synthesis and analysis We mapped the data according to the vaccine categories and intervention outcomes. The vaccines were further categorised into comparisons as reported in the included studies. We categorised outcomes into efficacy/effectiveness, safety, and immunogenicity related to maternal or infant health, and indicated the study design of each study. We used Microsoft PowerPoint® to create the evidence map. Assessment of the risk of bias and certainty of evidence In contrast to systematic reviews, scoping reviews do not usually include a risk of bias assessment or the application of GRADE to assess the certainty of evidence 37,38 . Therefore, we did not assess the risk of bias and certainty of evidence. Declarations Data Availability: The datasets used and/or analysed during the current study are available from the corresponding author upon request. Acknowledgments: This review was commissioned by the European Health and Digital Executive Agency (HaDEA) for the European Centre for Disease Prevention and Control (ECDC), as part of the activities of the ECDC NITAG Collaboration, in close cooperation with the European Commission (No HADEA/2021/OP/0011). The commissioning and production of this review was coordinated by Kate Olsson (ECDC). The EU4Health Programme funded this review under a service contract with the European Health and Digital Executive Agency (HaDEA). The information and views set out in this review are those of the author(s) and do not necessarily reflect the official opinion of HaDEA or the European Commission. Neither HaDEA or the European Commission nor any person acting on their behalf may be held responsible for the use which may be made of the information contained therein. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. We gratefully acknowledge Sandra Hummel for project administration and formatting. We thank Kavita Kothari, consultant to the Evidence Synthesis Ireland, University of Galway, for peer review of the MEDLINE search strategy. We acknowledge the use of ChatGPT for language editing in preparing this review. Author Contributions: IK developed the search strategy and conducted electronic literature searches. IS, AD, CNB, LP, AG, CC, and LA conducted literature screening and data extraction. IS wrote the first draft of the manuscript. AD, CNB, LP, AG, CC, and LA critically revised the manuscript. GG, GW, KMSUR, PET, DD, KO, MK and the ECDC NITAG Collaboration working group members (AA, ACC, DF, JDL, SR, KM, GP, MRM, JR, LSC, SS, AFD) designed and advised this project and critically revised the manuscript. All authors approved the final version of the manuscript. Competing Interests: All authors declare that they have no conflicts of interest to disclose. References Wei, S. Q., Bilodeau-Bertrand, M., Liu, S. & Auger, N. The impact of COVID-19 on pregnancy outcomes: a systematic review and meta-analysis. CMAJ 193, E540-e548 (2021). https://doi.org:10.1503/cmaj.202604 Yeung, K. H. T., Duclos, P., Nelson, E. A. 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Additional Declarations No competing interests reported. Supplementary Files Maternalscopingsupplementarymaterialv304122025.docx Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 26 Apr, 2026 Reviews received at journal 25 Apr, 2026 Reviewers agreed at journal 25 Apr, 2026 Reviews received at journal 24 Apr, 2026 Reviews received at journal 31 Mar, 2026 Reviewers agreed at journal 16 Mar, 2026 Reviewers agreed at journal 16 Mar, 2026 Reviewers agreed at journal 15 Mar, 2026 Reviewers agreed at journal 13 Mar, 2026 Reviewers agreed at journal 12 Mar, 2026 Reviewers invited by journal 11 Mar, 2026 Editor assigned by journal 11 Mar, 2026 Submission checks completed at journal 04 Mar, 2026 First submitted to journal 02 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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08:09:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1730948,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9013883/v1/5e8785a6-6f3e-4b59-b02e-9e581c1b8eb4.pdf"},{"id":104690429,"identity":"f8ff1840-19e2-4436-b3ef-deeb6869a87b","added_by":"auto","created_at":"2026-03-16 06:07:36","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":3016069,"visible":true,"origin":"","legend":"","description":"","filename":"Maternalscopingsupplementarymaterialv304122025.docx","url":"https://assets-eu.researchsquare.com/files/rs-9013883/v1/500c4d88417b2f356d8f8b8a.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Maternal Vaccination against COVID-19, Influenza, Pertussis, and Respiratory Syncytial Virus: A Scoping Review","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePregnancy and early infancy are periods of increased vulnerability to infection, which can lead to severe complications for the mother, foetus, or young infant. Infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or seasonal influenza virus have been shown to increase the risk of adverse pregnancy outcomes such as preterm birth, or stillbirth \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Newborns and young infants are also at significant risk of severe, potentially fatal complications after infections with \u003cem\u003eBordetella pertussis\u003c/em\u003e or Respiratory Syncytial Virus (RSV) \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. As of April 2024, increasing pertussis cases were being reported in the European Union and the European Economic Area (EU/EEA), with the highest burden in infants\u0026thinsp;\u0026lt;\u0026thinsp;1 year of age in the majority of EU/EEA countries, indicating the importance of significantly strengthening maternal vaccination approaches\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. RSV accounted for 1.4\u0026nbsp;million hospital admissions and 45,700 deaths globally in infants aged 0\u0026ndash;6 months in 2019 \u003csup\u003e6\u003c/sup\u003e. In the European Union (EU), RSV was estimated to affect 72 out of 1000 infants under the age of two months and affecting especially children under the age of 5 \u003csup\u003e7\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eDue to the functional immaturity, the newborn\u0026rsquo;s immune system characteristically lacks reactivity to multiple microorganisms to prevent excessive inflammatory responses \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Newborns and young infants can be protected from serious infections by the transplacental transfer of antibodies and other mediators of immunity from their mothers during pregnancy and through maternal antibodies transferred to the child through breastfeeding \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Vaccination during pregnancy boosts maternal levels of pathogen-specific antibodies, providing protection to both mother and infant during the first months of life \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eMany EU countries have introduced national vaccination programmes designed for pregnant women, with some differences in the recommended gestational timing of vaccination and the choice of vaccines \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. Mapping the maternal vaccination literature is a first step to understanding potential evidence gaps, any significant updates to the literature or new evidence on this topic.\u003c/p\u003e \u003cp\u003eThe aim of this scoping review was to identify evidence gaps and support decision-makers in choosing priority areas for subsequent evidence synthesis by identifying and mapping the existing research landscape of the efficacy, effectiveness, safety and immunogenicity of maternal vaccination against COVID-19, influenza, pertussis, and RSV, including available literature examining these outcomes in relation to the optimal timing for administration of these vaccinations during pregnancy. Optimal timing is the vaccination window in pregnancy that provides the greatest effectiveness, antibody transfer, and safety for mother and infant. This review did not aim to appraise study quality, estimate pooled effects, or judge benefits or safety.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eOur literature searches across various databases and registries identified 6,523 records after removal of duplicates.\u0026nbsp;After\u0026nbsp;screening titles and abstracts, 5,411 records were deemed irrelevant and excluded. We identified one record via citation searching. We then conducted a full-text review of 1,102 records, leading to the exclusion of 466 records based on a detailed assessment. Ultimately, our review incorporated 636 publications (637 records): 541 primary studies and 95 evidence syntheses. The study selection process is visually summarised in Figure 1. Supplementary information 1 lists the studies excluded by full-text assessment, with the corresponding reasons for exclusion.\u003c/p\u003e\n\u003cp id=\"_Toc178241422\"\u003eFigure 1: PRISMA flow diagram illustrating the study selection process*\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e*adapted from Page et al.\u0026nbsp;\u003c/em\u003e\u003cem\u003e\u003csup\u003e12\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAbbreviation: n = number of records\u003c/em\u003e\u003c/p\u003e\n\u003ch2\u003eCOVID-19\u003c/h2\u003e\n\u003cp\u003eWe identified 261 primary studies (2 RCTs, 225 controlled cohort studies, 17 case-control studies, 5 test-negative design studies, and 12 cross-sectional studies) and 45 evidence syntheses (41 systematic reviews, 2 rapid reviews, and 2 scoping reviews) addressing the effectiveness, safety, and/or immunogenicity of COVID-19 vaccination in pregnant participants. The optimal timing of maternal COVID-19 vaccination in relation to the outcomes including immunogenicity, clinical outcomes and/or safety, was examined in 101 of these publications. Supplementary information 2 lists the included studies for maternal COVID-19 vaccination. Five primary studies and one evidence synthesis were available as preprints only. Seven studies are ongoing, or the results have not been published yet (see Supplementary information 3).\u003c/p\u003e\n\u003cp\u003eMost studies\u0026nbsp;compared maternal COVID-19 vaccination against no vaccination (191 primary studies and 38 evidence syntheses). One study compared COVID-vaccination with influenza vaccination. Eighty-six studies evaluated a different number of doses of maternal COVID-19 vaccination, 39 analysed different types of COVID-19 vaccines, and 11 evidence syntheses examined either different dosages, types of vaccines, or both. Thirty- seven studies compared maternal COVID-19 vaccination with maternal SARS-CoV-2 infection.\u003c/p\u003e\n\u003cp\u003eEighty-three publications (64 primary studies and 19 evidence syntheses) reported on maternal effectiveness outcomes. Infant effectiveness outcomes were reported in 31 publications. Maternal safety outcomes were reported in 148 publications, while infant safety outcomes were reported in 174 publications. Ninety-three publications reported maternal immunogenicity data, and 80 publications reported infant immunogenicity outcomes.\u003c/p\u003e\n\u003cp\u003eFigure 2 and Supplementary information 4 display all studies and systematic reviews that were identified for maternal COVID-19 vaccination.\u003c/p\u003e\n\u003cp\u003eFigure 2: Evidence map for maternal COVID-19 vaccinations\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e*Different types of vaccines, and different numbers of doses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNumbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, yellow cohort studies, red cross-sectional studies, brown evidence synthesis, and grey test-negative design studies.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAbbreviations: COVID-19 = Coronavirus disease of 2019; vs = versus\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFour systematic reviews on maternal COVID-19 vaccination were published in 2024 \u003csup\u003e13-16\u003c/sup\u003e. They compared different types of COVID-19 vaccines (Astra Zeneca, BioNTech/Pfizer, Janssen, Moderna, Sinovac, Sinopharm, Covaxin; Johnson \u0026amp; Johnson) against no vaccination, as well as the timing \u003csup\u003e13,15\u003c/sup\u003e, vaccine types \u003csup\u003e15,16\u003c/sup\u003e and total number of administered doses of COVID-19 vaccines during pregnancy \u003csup\u003e14-16\u003c/sup\u003e. Fern\u0026aacute;ndez-Garc\u0026iacute;a et al. \u003csup\u003e14\u003c/sup\u003e analysed 24 studies with 730,269 participants, Ciapponi et al. \u003csup\u003e16\u003c/sup\u003e 137 studies with 638,791 participants, Wang et al. \u003csup\u003e13\u003c/sup\u003e 39 studies with more than 1,600,000 participants, and Lei et al. \u003csup\u003e15\u003c/sup\u003e 82 studies with 3,676,654 participants. All studies included in the reviews are observational studies. The authors reviewed mRNA, viral vector, and inactivated vaccines administered during various trimesters (1-3 doses). While the systematic reviews by Fern\u0026aacute;ndez-Garc\u0026iacute;a et al. \u003csup\u003e14\u003c/sup\u003e, Ciapponi et al. \u003csup\u003e16\u003c/sup\u003e and Lei et al. \u003csup\u003e15\u003c/sup\u003e focused on the efficacy/effectiveness and safety outcomes for both mother (including/comprising infection, severe COVID-19 disease, hospital admission, death, miscarriage, caesarean section, postpartum haemorrhage, gestational diabetes, hypertensive disorders of pregnancy, and any other adverse events) and infant (including congenital malformation, infection, stillbirth, preterm birth, admission to neonatal intensive care unit, small for gestational age, and neonatal death), Wang et al. \u003csup\u003e13\u003c/sup\u003e included only safety outcomes for the mother (including miscarriage, caesarean delivery, emergency caesarean delivery, very preterm birth (\u0026lt;32 weeks), preterm birth (\u0026lt;37 weeks), spontaneous preterm birth, medically indicated preterm birth, placental abruption, postpartum haemorrhage, and preeclampsia) and infant (including stillbirth, meconium-stained amniotic fluid, small for gestational age, 5-min Apgar scores of less than 7, low birth weight (\u0026lt;2500 g), very low birth weight (\u0026lt;1500g), neonatal intensive care unit admission, and respiratory complications). Supplementary Information 5 displays the study and population characteristics of the selected systematic reviews, and Supplementary Information 6 displays the reported outcomes.\u003c/p\u003e\n\u003ch2 id=\"_Toc178241425\"\u003eInfluenza\u003c/h2\u003e\n\u003cp\u003eIn total, 190 publications were included, comprising 161 primary studies (14 RCTs, 117 cohort studies, 20 case-control studies, five cross-sectional studies, five test-negative design studies)\u0026nbsp;and twenty-nine systematic reviews; Supplementary information 7). One study was published as a preprint. We identified six ongoing studies, or the results have not been published yet (Supplementary information 3).\u003c/p\u003e\n\u003cp\u003eOf the 190 publications, 167 compared vaccination against no vaccination (140 primary studies and 27 systematic reviews). Among these, there were seven placebo-controlled RCTs and six systematic reviews, including placebo-controlled studies. Additionally, 21 studies and three systematic reviews compared one vaccine with another vaccine or vaccine type. The timing of vaccination was investigated in nine case-control studies, 57 cohort studies, one cross-sectional study, two RCTs, two test-negative design study and in eight systematic reviews.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMaternal efficacy/effectiveness outcomes were reported in 41 publications. Forty-eight publications reported infant efficacy/effectiveness outcomes. Eighty-three publications addressed maternal safety outcomes, and 135 reported infant safety outcomes. Additionally, 25 publications provided data on maternal immunogenicity, while 22 reported infant immunogenicity outcomes. Figure 3 and Supplementary information 8 display all studies and systematic reviews that were identified for maternal influenza vaccination.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 3: Evidence map for influenza vaccinations\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e*Other vaccines\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNumbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, yellow cohort studies, red cross-sectional studies, brown systematic reviews, and grey test-negative design studies.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAbbreviation: vs = versus\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe two most recent systematic reviews on influenza vaccination during pregnancy were published in 2023 \u003csup\u003e17\u003c/sup\u003e and 2021 \u003csup\u003e18\u003c/sup\u003e. The systematic review by Bansal et al. \u003csup\u003e18\u003c/sup\u003e included fourteen studies involving over 53,000 healthy pregnant participants who received trivalent inactivated seasonal influenza vaccine, another commercially available influenza vaccine, pneumococcal vaccine, meningococcal vaccine, placebo, or no vaccination. Wolfe et al. \u003csup\u003e17\u003c/sup\u003e examined 63 observational studies with over 943,598 participants, including several comparisons but focusing their primary analysis on trivalent or quadrivalent seasonal influenza vaccines against no vaccination in pregnant women. Bansal et al. \u003csup\u003e18\u003c/sup\u003e assessed the optimal timing of vaccination uptake for vaccine effectiveness across all trimesters.\u0026nbsp;The maternal outcomes of interest included vaccine efficacy in preventing infection and hospitalisation rates due to severe influenza, rates of febrile illnesses, immunogenicity, and adverse events. In infants, outcomes focused on vaccine efficacy in providing protection against influenza, hospitalisation rates due to influenza infection, the rate of febrile illnesses, the risk of low birth weight and preterm birth, and immunogenicity. The focus of Wolfe et al. \u003csup\u003e17\u003c/sup\u003e was on maternal safety outcomes, such as non-obstetric serious adverse events, and infant safety outcomes like spontaneous abortion, stillbirth, preterm birth, small-for-gestational-age birth, low birth weight, and congenital anomalies.\u0026nbsp;Further details about characteristics and outcomes reported by the two systematic reviews are provided in Supplementary information 5 and 6.\u003c/p\u003e\n\u003ch2 id=\"_Toc178241428\"\u003ePertussis\u003c/h2\u003e\n\u003cp\u003eWe identified 113 primary studies and 20 systematic reviews addressing the efficacy/effectiveness, safety, and/or immunogenicity of pertussis vaccination in pregnant participants (Supplementary information 9). Of the 113 primary studies, 17 were RCTs, 73 were controlled cohort studies, one was a test-negative design study, three were cross-sectional studies, and 19 were case-control studies. Five studies were ongoing, and the results were not yet published at the time of analysis (Supplementary information 3).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNinety-five studies compared maternal pertussis vaccination against no vaccination, four of them compared vaccination against a placebo. Nine studies compared pertussis vaccination against other vaccines or vaccine types. Fifteen systematic reviews compared vaccination against placebo/no vaccination, and three against placebo/other vaccines.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eInfant efficacy/effectiveness was reported in 43 publications. Safety outcomes were reported in 73 publications for mother and/or infant. Thirty-seven publications reported maternal immunogenicity outcomes. Infant immunogenicity outcomes were reported by 59 publications. The timing of vaccination on the different outcomes was evaluated in 49 publications. Figure 4 and Supplementary information 10 display all studies and systematic reviews we identified for maternal pertussis vaccination.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 4: Evidence map for pertussis vaccinations\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e*Different type of vaccines, and different number of doses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNumbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, yellow cohort studies, red cross-sectional studies, brown systematic review, and grey test-negative design studies.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAbbreviation: vs = versus\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSix systematic reviews examining maternal pertussis were published between 2021 and 2025 \u003csup\u003e19-24\u003c/sup\u003e. The reviews compared maternal pertussis vaccination against no vaccination, standard or other vaccines \u003csup\u003e19-23\u003c/sup\u003e, and four reviews also compared against placebo \u003csup\u003e19,21-23\u003c/sup\u003e.\u0026nbsp;One review compared different timepoints of maternal vaccination\u0026nbsp;\u003csup\u003e24\u003c/sup\u003e, two reviews provided subgroup analysis on timing\u0026nbsp;\u003csup\u003e19,23\u003c/sup\u003e.\u0026nbsp;Nguyen et al.\u0026nbsp;\u003csup\u003e20\u003c/sup\u003e included 26 studies (RCTs, cohort studies, case-control studies, and case series) with more than 350,000 pregnant participants and their offspring, Gidengil et al.\u0026nbsp;\u003csup\u003e19,25\u003c/sup\u003e included four RCTs, thirteen cohort studies, and one case-control study covering 1,932,709 pregnant women with vaccination between 28 to 32 gestational weeks, Andersen et al.\u0026nbsp;\u003csup\u003e21\u003c/sup\u003e included 19 studies (six RCTS and 13 cohort studies) with 1,749,463 pregnant women, and Simayi et al. 2022\u0026nbsp;\u003csup\u003e22\u003c/sup\u003e included 6 RCTs with overall 1,400 women with uncomplicated singleton pregnancies with vaccination between 18 to 36 gestational weeks, Shi et al.\u0026nbsp;\u003csup\u003e23\u003c/sup\u003e included 7 RCTs and 10 case-control studies with 3,704 pregnant women, and de Weerdt\u0026nbsp;\u003csup\u003e24\u003c/sup\u003e included 35 studies (4 RCTS and 31 observational studies) with 416,278 pregnant women. The systematic reviews by Gidengil et al\u0026nbsp;\u003csup\u003e19\u003c/sup\u003e, Nuygen et al.\u0026nbsp;\u003csup\u003e20\u003c/sup\u003e, and Shi et al.\u0026nbsp;\u003csup\u003e23\u003c/sup\u003e assessed the vaccines Adacel\u003csup\u003e\u0026reg;\u003c/sup\u003e (Sanofi) or Boostrix\u003csup\u003e\u0026reg;\u003c/sup\u003e (GlaxoSmithKline), while the others did not report the type of vaccines that were used in the studies. Two systematic reviews focused on maternal safety outcomes (including non-pertussis infection, spontaneous abortion, chorioamnionitis, death, autoimmune disease, cardiovascular events, diabetes, eclampsia/preeclampsia, encephalitis/encephalopathy, Guillain-Barr\u0026eacute; syndrome, preterm labour, reproductive system events, seizures, and other adverse events (1 cohort study)) and infant safety outcomes (including non-pertussis infections, neonatal death, stillbirth, autism or attention deficit hyperactivity disorder (ADHD) in infants, birth defects, cardiovascular events, death in infants, encephalitis/encephalopathy, intussusception, meningitis, seizure, stroke, low birthweight, preterm birth, small or large for gestational age, respiratory distress syndrome, transient tachypnea of newborn, tachycardia or bradycardia, hemolytic disease, neonatal jaundice, anaemia, syndrome of infant of mother with gestational diabetes, and hypoglycaemia)\u0026nbsp;\u003csup\u003e19,21\u003c/sup\u003e. One systematic review focused on maternal and infant safety (severe adverse events) and infant immunogenicity (pertussis IgG)\u0026nbsp;\u003csup\u003e22\u003c/sup\u003e, three addressed infant efficacy/effectiveness (incidence of pertussis), maternal and infant safety outcomes (severe adverse events), and infant immunogenicity (pertussis IgG)\u0026nbsp;\u003csup\u003e20,23,24\u003c/sup\u003e. The review by De Weerdt et al.\u0026nbsp;\u003csup\u003e24\u003c/sup\u003e additionally provided information on maternal immunogenicity outcomes. Supplementary information 5 displays the study and population characteristics of these systematic reviews, and Supplementary information 6 displays reported outcomes.\u003c/p\u003e\n\u003ch2 id=\"_Toc178241431\"\u003eRespiratory syncytial virus (RSV)\u003c/h2\u003e\n\u003cp\u003eWe identified 20 primary studies and 11 evidence syntheses addressing the efficacy, effectiveness, safety, and/or immunogenicity of vaccination against RSV in pregnant women (Supplementary information 11). Eleven of the primary studies were RCTs, two controlled cohort studies, three were case-control studies, three were test-negative design studies, and one was a cross-sectional study. We identified 11 ongoing studies and one preprint at the time of analysis (Supplementary information 3).\u003c/p\u003e\n\u003cp\u003eAll RCTs compared maternal RSV vaccination against placebo, most observational studies against no vaccination, and all evidence syntheses against no vaccination or placebo. Three RCTs reported on maternal efficacy outcomes. Infant efficacy from RSV infection or RSV-associated hospitalisation was reported in 13 studies and seven systematic reviews. Safety outcomes for mother and/or infant were reported in 14 studies and 11 evidence syntheses. Nine studies and three systematic reviews examined maternal and infant immunogenicity outcomes. Infant immunogenicity was the only outcome assessed by one case-control study. The optimal timing of RSV vaccination during pregnancy was investigated in three studies. Figure 5 and Supplementary information 12 display all studies and systematic reviews we identified for maternal RSV vaccination.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 5: Evidence map for RSV vaccinations\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e*Other vaccine\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNumbers inside the bubbles indicate how many studies addressed that research question. Green indicates RCTs, blue case-control studies, and brown systematic reviews\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviations:\u003c/strong\u003e RSV = Respiratory syncytial virus; vs = versus\u003c/p\u003e\n\u003cp\u003eThe systematic reviews by Mapindra et al. \u003csup\u003e26\u003c/sup\u003e, Phijffer et al. 2024 \u003csup\u003e27\u003c/sup\u003e, and Alandijany et al. 2025 \u003csup\u003e28\u003c/sup\u003e provide the most recent and comprehensive systematic reviews we identified. Mapindra et al. \u003csup\u003e26\u003c/sup\u003e and \u0026nbsp;Phijffer et al. 2024 \u003csup\u003e27\u003c/sup\u003e both included six RCTs comparing RSV vaccination versus placebo, with five RCTs overlapping between the reviews. Alandijany et al. 2025 \u003csup\u003e28\u003c/sup\u003e included three RCTs and two observational studies comparing RSV vaccination against placebo or active control. Mapindra et al. \u003csup\u003e26\u003c/sup\u003e examined 12,734 uncomplicated singleton pregnancies, Phijffer et al. 2024 \u003csup\u003e27\u003c/sup\u003e included 17,991 participants, and Alandijany et al. 2025 \u003csup\u003e28\u003c/sup\u003e included 19,400 pregnant women. They received a single dose (50, 60, 120, or 240 \u0026mu;g) of the adjuvanted (Wyeth Lederle, NovaVax, Pfizer) or unadjuvanted RSV vaccine (GlaxoSmithKline, Pfizer). The systematic reviews by Mapindra et al. \u003csup\u003e26\u003c/sup\u003e and Alandijany et al. 2025 \u003csup\u003e28\u003c/sup\u003e assessed RSV infection and RSV-related hospitalisations in infants, maternal safety, and maternal and infant immunogenicity outcomes, while the systematic review by Phijffer et al. 2024 \u003csup\u003e27\u003c/sup\u003e reported infant RSV hospitalisation, and maternal and infant safety outcomes. Supplementary information 5 displays the study and population characteristics of these systematic reviews, and Supplementary information 6 displays reported outcomes.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis scoping review mapped the evidence based on 541 primary studies and 95 evidence syntheses addressing the efficacy, effectiveness, safety, and immunogenicity of maternal COVID-19, influenza, pertussis, and RSV vaccinations. Per‑vaccine counts are not mutually exclusive because some evidence syntheses include multiple pathogens. The largest evidence base exists for maternal COVID-19 vaccination, followed by maternal influenza, pertussis, and RSV vaccination. Optimal timing of vaccination during pregnancy was investigated in 226 studies (101 COVID-19, 79 influenza, 49 pertussis, three RSV), with 29 studies (seven COVID-19, six influenza, five pertussis, 11 RSV) still ongoing or awaiting publication at the time of analysis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe evidence for maternal COVID-19 vaccination relies primarily on observational studies comparing vaccination against no vaccination. Most of these studies assessed maternal efficacy and effectiveness, as well as maternal and infant safety outcomes. Four up-to-date systematic reviews compare different commercially available COVID-19 vaccines to no vaccination before and/or during pregnancy. They cover a broad range of maternal and infant efficacy/effectiveness outcomes, as well as safety outcomes for both mother and infant. Two reviews also include outcome comparisons across different trimesters of pregnancy. Interpretation of observational signals in pregnancy requires caution. Healthy-vaccinee effects, gestational–age–dependent vaccine uptake, and time-varying confounding can bias associations toward a benefit of vaccination. Bias can also arise if exposure is defined after an outcome‑free interval. Misclassification of exposure timing or obstetric outcomes, and incomplete adjustment for parity, comorbidity, and socioeconomic status, further limit causal inference. These considerations support prioritising well‑adjusted designs and, where feasible, randomised or quasi‑experimental evidence.\u003c/p\u003e\n\u003cp\u003eIn contrast to maternal COVID-19 vaccination, we identified 14 placebo-controlled and comparative effectiveness RCTs for maternal influenza vaccination that report on maternal and infant efficacy/effectiveness and safety outcomes. However, most studies are observational studies, reporting safety outcomes in infants and pregnant women as well as maternal and infant efficacy/effectiveness. The most recent systematic reviews cover search periods until May or June 2021, but 44 primary studies have been published since 2021. The timing of maternal influenza vaccinations is not studied in the selected reviews. However, eight older systematic reviews and 71 primary studies are available on timing.\u003c/p\u003e\n\u003cp\u003eThe evidence for maternal pertussis vaccination rests on 17 placebo-controlled, no-vaccination, and comparative effectiveness RCTs. The RCTs focus on safety and immunogenicity outcomes. A large body of observational studies also reported efficacy/effectiveness outcomes. The most recent systematic review covers the search period up to February 2025. One systematic review published in 2024 specifically focuses on the timing of pertussis vaccination, one systematic review on this topic is registered \u003csup\u003e29\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eWe identified 20 studies on maternal RSV vaccination, 11 of which were RCTs. They report efficacy/effectiveness outcomes for infants, and safety and immunogenicity outcomes for both infants and mothers. Three studies on the timing of RSV vaccination during pregnancy are available. The most recent systematic reviews cover until 2023 and 2025 with two focusing on evidence from RCTs.\u003c/p\u003e\n\u003cp\u003eThis scoping review offers an overview of the current evidence for maternal COVID-19, influenza, and pertussis vaccinations. The evidence gap maps show, at a high abstract level, that existing studies cover maternal and infant efficacy/effectiveness, safety, and immunogenicity outcomes.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe did not appraise risk of bias, estimate pooled effects, or draw conclusions about clinical effectiveness. Interpretation of the observational literature is limited by confounding and design issues; addressing those questions requires a focused systematic review with appropriate critical appraisal and, where possible, meta‑analysis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe evidence for optimal timing of COVID-19, influenza, and pertussis vaccination during pregnancy also appears exhaustive but the evidence is often derived from subgroup analyses. In contrast, the body of evidence for maternal RSV vaccination is relatively sparse but given its only recent approval in August 2023 by the EMA \u003csup\u003e30\u003c/sup\u003e and FDA \u003csup\u003e31\u003c/sup\u003e not surprising. Although some RCTs focus on infant efficacy, maternal and infant safety, and immunogenicity, there is a clear need for more observational studies and research on the optimal timing of RSV vaccination during pregnancy. The review also points out that, while recent systematic reviews are available for maternal COVID-19, influenza, and pertussis vaccinations, the publication of numerous new primary studies about RSV vaccinations since the last search date calls for updated reviews. For RSV vaccination, although recent systematic reviews exist, the rapid pace of ongoing research in this area suggests that more studies are likely to be published soon, necessitating continuous updates to the evidence base. Finally, the quality of these systematic reviews remains to be assessed, emphasising the importance of ensuring that the evidence they provide is both reliable and comprehensive for guiding maternal vaccination practices.\u003c/p\u003e\n\u003cp\u003eThis review has several limitations. First, although we developed and uploaded a protocol for this review on the Open Science Framework (https://osf.io/v3rgt/), we had to make some amendments throughout the review process to tackle the large volume of evidence. Thus, we could not do as detailed a data extraction for all studies as originally planned. With the two-staged approach to data extraction with a focus on recent and comprehensive systematic reviews, we relied on data provided by these reviews, which sometimes lacked information on dose, vaccine types, or patient characteristics. Second, another adaptation we made to the protocol was that we did not include and extract data on ongoing clinical trials. Clinical trial registrations provide useful information for characterising the research dynamic and activity in a particular field. We listed the identified clinical trial registrations in Supplementary information 3 but officially excluded them from the list of included studies to reduce the scope of this review. Despite these amendments, we believe that our approach supports decision-makers in choosing a subsequent systematic review topic. Third, because we received a large volume of evidence through database searches, we did not conduct further supplementary searches, including reference list checking, forward citation tracking, and searching the websites of regulatory agencies. It is, therefore, possible that we missed some studies that met our inclusion criteria. Finally, we excluded studies that provided only subgroup analyses of pregnant women, as their inclusion would have necessitated an excessively broad search strategy encompassing all studies involving individuals receiving vaccination against COVID-19, influenza, pertussis, and RSV.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe aim of this scoping review was to identify evidence gaps in maternal vaccination research and highlight priority areas for future evidence synthesis by systematically mapping the existing literature regarding study design, comparisons, outcomes, and timing of vaccination of both primary studies and systematic reviews. \u0026nbsp;This scoping review does not address the outcome estimates of immunogenicity, efficacy, effectiveness and/or safety of COVID-19, influenza, pertussis, or RSV vaccination given during pregnancy. The unexpectedly large number of studies we identified highlights the need to focus and prioritise the scope of a subsequent systematic review to a manageable level. This can be achieved by narrowing the study designs, comparators, and outcomes, with an emphasis on identifying the most useful and specific evidence relevant to decision-making. Although there is limited evidence for specific outcomes, the availability of sufficient studies on maternal and infant efficacy/effectiveness outcomes across all four types of vaccinations indicates that reliance on immunogenicity data may not be necessary nor desirable. A further challenge for a subsequent review is the dynamic nature of this research field. This is particularly relevant for RSV vaccination, as the RSV vaccine ABRYSVO was approved by the EMA and FDA in 2023 \u003csup\u003e30,31\u003c/sup\u003e. We identified several ongoing studies for the other three maternal vaccinations available for COVID-19, influenza and pertussis. Given the volume of efficacy, effectiveness and safety data, a follow‑on systematic review can prioritise outcome‑specific questions, for example, trimester‑specific risks of preterm birth, stillbirth, and severe maternal disease. We recommend two syntheses: timing of COVID‑19 booster vaccination during pregnancy and effectiveness and safety of coadministration of influenza and pertussis vaccines.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eWe conducted this scoping review following the \u003cem\u003eJoanna Briggs Institute (JBI) Manual for Evidence Synthesis\u003c/em\u003e, Chapter 11: Scoping reviews \u003csup\u003e32,33\u003c/sup\u003e. Consistent with scoping methodology, we mapped and described evidence characteristics and outcome domains; we did not synthesise effect estimates, appraise study quality, or make judgments about efficacy, effectiveness, or safety. When reporting the results, we consulted the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) Extension for Scoping Reviews (PRISMA-ScR) \u003csup\u003e34\u003c/sup\u003e (Supplementary information 13). The review protocol was registered with the Open Science Framework (https://osf.io/v3rgt/).\u003c/p\u003e\n\u003ch2\u003eEligibility criteria\u003c/h2\u003e\n\u003cp\u003eWe included studies assessing the efficacy/effectiveness, safety, and immunogenicity of maternal vaccination against COVID-19, influenza, pertussis, and RSV in pregnant women irrespective of their health status. Studies had to use whole pathogen vaccines (inactivated), component vaccines (based on recombinant protein subunits or other immunogenic components of pathogens, conjugated vaccines) and vector-based vaccines. Although initially intended to include, we formally excluded clinical trial registrations but provided a list in Supplementary information 3 due to the large number of studies we identified.\u0026nbsp;Table 1 presents the inclusion and exclusion criteria in detail.\u003c/p\u003e\n\u003cp id=\"_Toc178241410\"\u003eTable 1: Inclusion and exclusion criteria\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eInclude\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eExclude\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePopulation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePregnant people (any pregnancy trimester)\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e\u0026nbsp;\u0026nbsp;\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNon-pregnant people, mothers in postpartum period, breastfeeding mothers\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eIntervention\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eKQ1: Inactivated vaccination against COVID-19, influenza, pertussis (as combination vaccine, e.g. DTaP, Tdap, Tdap-IPV), RSV\u003c/p\u003e\n \u003cp\u003eAny type of vaccine (i.e., valency), any dose, any combination\u003c/p\u003e\n \u003cp\u003eKQ1a: timing of vaccination (e.g., different trimesters)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAny other vaccine not mentioned (only if included in combination vaccine e.g. diphtheria and tetanus in diphtheria–pertussis–tetanus vaccine)\u003c/p\u003e\u0026nbsp;\u0026nbsp;\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eContext\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMiddle- and high-income countries according to the World Bank classification\u003csup\u003e2\u0026nbsp;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eLow-income countries according to the World Bank classification\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eOutcomes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAny maternal, neonatal (preterm and term) or infant outcome (short- and long-term):\u003c/p\u003e\n \u003cp\u003eefficacy and/or effectiveness outcome (e.g., infection rate, severe infection rate, mortality due to infection);\u003c/p\u003e\n \u003cp\u003esafety outcome (e.g., preterm birth incidence, low birthweight, miscarriage, stillbirth, congenital abnormalities, solicited and unsolicited overall adverse events, specific adverse events, serious adverse events); and\u003c/p\u003e\n \u003cp\u003eimmunogenicity outcomes (e.g., geometric mean ratio)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo restrictions\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eStudy designs\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eRCTs\u003c/p\u003e\n \u003cp\u003eControlled clinical trials\u003c/p\u003e\n \u003cp\u003eNon-randomised studies of interventions (controlled cohort studies,\u003c/p\u003e\n \u003cp\u003ecase-control studies, including test-negative design studies, controlled cross-sectional studies with a retrospective assessment of vaccination status)\u003c/p\u003e\n \u003cp\u003eRapid/Living/Scoping/Systematic Reviews\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAny other study design\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDocument types\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePublished articles\u003c/p\u003e\n \u003cp\u003ePreprints\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePosters, conference abstracts, study protocols, books or book chapters, editorials, clinical trial registrations\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2000 onwards\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBefore 2000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eLanguage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo restrictions\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviations:\u003c/strong\u003e COVID-19=Coronavirus disease of 2019; DTaP=Diphtheria, tetanus, and pertussis Tdap=Tetanus, Diphtheria, and Pertussis; TdapIPV=Diphtheria, tetanus, pertussis and poliomyelitis; KQ=Key question; RCTs= Randomised controlled trials; RSV=Respiratory syncytial virus;\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eExcluding studies providing only subgroup analyses of pregnant individuals\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e²https://datahelpdesk.worldbank.org/knowledgebase/articles/906519-world-bank-country-and-lending-groups\u003c/p\u003e\n\u003ch2\u003eLiterature searches\u003c/h2\u003e\n\u003cp id=\"_Toc150957369\"\u003eAn expert information specialist (IK) searched for studies in MEDLINE (via Ovid), Cochrane/CENTRAL and Cochrane Database of Systematic Reviews (CDSR) (via Cochrane Library/Wiley), Embase (via Embase.com/Elsevier), COVID-19 L*OVE (app.iloveevidence.com/loves/5e6fdb9669c00e4ac072701d), Epistemonikos (epistemonikos.org), and the International HTA Database (database.inahta.org) published between 2000 to 15 April 2024. We limited our search to those published in the year 2000 and onwards to capture studies on influenza or pertussis vaccines relevant to today. We did not apply any language restrictions. The search strategies were peer-reviewed by a second information specialist, following the recommendations of Peer Review of Electronic Search Strategies (PRESS)\u0026nbsp;\u003csup\u003e35\u003c/sup\u003e. For each database, the date of the search, the search strategy, and the number of search results were documented (see Supplementary information 14). We also searched for completed but unpublished or ongoing studies in ClinicalTrials.gov\u0026nbsp;and the World Health Organization International Clinical Trials Registry Platform (ICTRP). We checked whether publications were available for eligible studies registered in ClinicalTrials.gov or ICTRP. To identify relevant preprints, we searched Europe PMC in addition to Embase (via Embase.com/Elsevier) for studies published from 2000 to 15 April 2024. We updated all database searches in October 2025 (searches until 28 October 2025). We did not conduct supplementary searches (reference list checking or forward citation searching) due to the large number of records identified from database searches.\u0026nbsp;\u003c/p\u003e\n\u003ch2 id=\"_Toc178241415\"\u003eStudy selection and management\u003c/h2\u003e\n\u003cp\u003eTwo reviewers independently screened the titles, abstracts, and relevant full-text articles against the predefined eligibility criteria using DistillerSR \u003csup\u003e36\u003c/sup\u003e (Evidence Partners, Ottawa, Canada). Conflicts were resolved by discussion or by consulting a third reviewer. The title and abstract screenings were piloted on a random subset of 50 search results. Full-text screening was piloted on four included studies. All results were tracked in an EndNote® 20 (Clarivate) software.\u003c/p\u003e\n\u003ch2 id=\"_Toc178241416\"\u003eData extraction\u003c/h2\u003e\n\u003cp\u003eDue to the large number of included studies, we performed a two-stage approach to data extraction. First, we extracted basic information from all included studies including study information, design, intervention, comparison, and outcomes. We defined each outcome category (maternal and infant efficacy/effectiveness, safety, immunogenicity) á priori (Supplementary Information 15: Categorisation of outcomes).\u0026nbsp;Second, we selected systematic reviews for each condition (COVID-19, influenza, pertussis, RSV) based on recency and comprehensiveness (i.e. number of outcomes covered). We documented reasons for not considering systematic reviews (Supplementary information 16). From selected systematic reviews, we extracted review characteristics (first author and publication year, search period, number and study design of included studies, funding sources, countries of included studies), participant characteristics (ethnicity, pregnancy week), intervention (type of vaccine, dosage), comparator (no intervention, placebo, other vaccines including type and dosage), timing of vaccination, and reported outcomes into standardised tables. One reviewer (AD, CNB, LA, CC, or LP) performed the data extraction, with a second reviewer (AD, CNB, LA, CC, or LP) checking all data extractions for completeness and accuracy.\u003c/p\u003e\n\u003ch2 id=\"_Toc150957380\"\u003eData synthesis and analysis\u003c/h2\u003e\n\u003cp\u003eWe mapped the data according to the vaccine categories and intervention outcomes. The vaccines were further categorised into comparisons as reported in the included studies. We categorised outcomes into efficacy/effectiveness, safety, and immunogenicity related to maternal or infant health, and indicated the study design of each study. We used Microsoft PowerPoint® to create the evidence map.\u0026nbsp;\u003c/p\u003e\n\u003ch2 id=\"_Toc178241417\"\u003eAssessment of the risk of bias and certainty of evidence\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eIn contrast to systematic reviews, scoping reviews do not usually include a risk of bias assessment or the application of GRADE to assess the certainty of evidence \u003csup\u003e37,38\u003c/sup\u003e. Therefore, we did not assess the risk of bias and certainty of evidence.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability:\u0026nbsp;\u003c/strong\u003eThe datasets used and/or analysed during the current study are available from the corresponding author upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u0026nbsp;\u003c/strong\u003eThis review was commissioned by the European Health and Digital Executive Agency (HaDEA) for the European Centre for Disease Prevention and Control (ECDC), as part of the activities of the ECDC NITAG Collaboration, in close cooperation with the European Commission (No HADEA/2021/OP/0011). The commissioning and production of this review was coordinated by Kate Olsson (ECDC). The EU4Health Programme funded this review under a service contract with the European Health and Digital Executive Agency (HaDEA). The information and views set out in this review are those of the author(s) and do not necessarily reflect the official opinion of HaDEA or the European Commission. Neither HaDEA or the European Commission nor any person acting on their behalf may be held responsible for the use which may be made of the information contained therein. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. We gratefully acknowledge Sandra Hummel for project administration and formatting. We thank Kavita Kothari, consultant to the Evidence Synthesis Ireland, University of Galway, for peer review of the MEDLINE search strategy. We acknowledge the use of ChatGPT for language editing in preparing this review.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u0026nbsp;\u003c/strong\u003eIK developed the search strategy and conducted electronic literature searches. IS, AD, CNB, LP, AG, CC, and LA conducted literature screening and data extraction. IS wrote the first draft of the manuscript. AD, CNB, LP, AG, CC, and LA critically revised the manuscript. GG, GW, KMSUR, PET, DD, KO, MK and the ECDC NITAG Collaboration working group members (AA, ACC, DF, JDL, SR, KM, GP, MRM, JR, LSC, SS, AFD) designed and advised this project and critically revised the manuscript. All authors approved the final version of the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests:\u003c/strong\u003e All authors declare that they have no conflicts of interest to disclose.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWei, S. Q., Bilodeau-Bertrand, M., Liu, S. \u0026amp; Auger, N. The impact of COVID-19 on pregnancy outcomes: a systematic review and meta-analysis. \u003cem\u003eCMAJ\u003c/em\u003e 193, E540-e548 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1503/cmaj.202604\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1503/cmaj.202604\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYeung, K. H. T., Duclos, P., Nelson, E. A. S. \u0026amp; Hutubessy, R. C. W. 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Version 2.35\u003c/em\u003e, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e%3Chttps://www.distillersr.com/%3E\u003c/span\u003e\u003cspan address=\"http://%3Chttps://www.distillersr.com/%3E\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeters, M. D. J. \u003cem\u003eet al.\u003c/em\u003e Updated methodological guidance for the conduct of scoping reviews. \u003cem\u003eJBI Evidence Synthesis\u003c/em\u003e 18 (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePollock, D. \u003cem\u003eet al.\u003c/em\u003e Undertaking a scoping review: A practical guide for nursing and midwifery students, clinicians, researchers, and academics. \u003cem\u003eJ. Adv. Nurs.\u003c/em\u003e 77, 2102\u0026ndash;2113 (2021).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-vaccines","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjvaccines","sideBox":"Learn more about [npj Vaccines](http://www.nature.com/npjvaccines/)","snPcode":"41541","submissionUrl":"https://submission.springernature.com/new-submission/41541/3?","title":"npj Vaccines","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-9013883/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9013883/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePregnancy and early infancy are periods of heightened vulnerability, with SARS-CoV-2 and influenza infections linked to adverse pregnancy outcomes, including preterm birth, and stillbirth. Maternal vaccination provides direct protection to mothers by active immunisation and to infants by passive immunisation. This scoping review mapped and described published literature on maternal vaccination against COVID-19, influenza, pertussis, and RSV, including which outcome domains were studied and the timing of vaccination examined, with the aim of identifying evidence gaps and supporting decision-makers in choosing priority areas for subsequent systematic review topics. A comprehensive literature search across multiple databases of studies published from January 2000 to October 2025 identified 636 publications (541 primary studies, 95 evidence syntheses). Studies on COVID-19 (261 studies, 45 reviews), influenza (161 studies, 29 reviews), pertussis (113 studies, 20 reviews), and RSV (20 studies, 11 reviews) were analysed. Substantial evidence on COVID-19, influenza, and pertussis vaccination on efficacy, effectiveness, safety and immunogenicity outcomes and the optimal timing of vaccination in relation to these outcomes during pregnancy is available. RSV vaccination evidence is limited. Updated systematic reviews would be helpful to clarify the optimal timing of COVID-19 vaccination and the effectiveness and safety of the coadministration of influenza and pertussis vaccines.\u003c/p\u003e","manuscriptTitle":"Maternal Vaccination against COVID-19, Influenza, Pertussis, and Respiratory Syncytial Virus: A Scoping Review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-16 06:07:30","doi":"10.21203/rs.3.rs-9013883/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-26T17:00:26+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-25T12:45:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"318534639683820250110518349348655675366","date":"2026-04-25T11:26:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-24T19:17:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-01T00:44:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"193982782634636287932946692051606948632","date":"2026-03-17T02:54:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"188507816396957662760054155482289402043","date":"2026-03-16T20:17:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"278381237634730478261002644103217388153","date":"2026-03-15T14:51:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"328397916257249712264364420381737412707","date":"2026-03-13T16:11:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"153864441483741487624790252532629623786","date":"2026-03-12T12:24:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-11T15:39:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-11T15:33:19+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-05T04:05:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"npj Vaccines","date":"2026-03-02T21:24:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-vaccines","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjvaccines","sideBox":"Learn more about [npj Vaccines](http://www.nature.com/npjvaccines/)","snPcode":"41541","submissionUrl":"https://submission.springernature.com/new-submission/41541/3?","title":"npj Vaccines","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3c248fe2-38f0-4570-a1ed-30c8eb451059","owner":[],"postedDate":"March 16th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[{"id":64419353,"name":"Health sciences/Diseases"},{"id":64419354,"name":"Health sciences/Health care"},{"id":64419355,"name":"Biological sciences/Immunology"},{"id":64419356,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2026-04-26T17:09:07+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-16 06:07:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9013883","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9013883","identity":"rs-9013883","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}