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This study explored the effect of SARS-CoV-2 infection and COVID-19 vaccination during pregnancy on neonatal outcomes among women from the general Dutch population. VASCO is an ongoing prospective cohort study aimed at assessing vaccine effectiveness of COVID-19 vaccination. Pregnancy status was reported at baseline and through regular follow-up questionnaires. As an extension to the main study, all female participants who reported to have been pregnant between enrolment (May-December 2021) and January 2023 were requested to complete an additional questionnaire on neonatal outcomes. Multivariable linear and logistic regression analyses were used to determine the associations between self-reported SARS-CoV-2 infection or COVID-19 vaccination during pregnancy and neonatal outcomes, adjusted for age, educational level, and presence of a medical risk condition. Infection analyses were additionally adjusted for COVID-19 vaccination before and during pregnancy, and vaccination analyses for SARS-CoV-2 infection before and during pregnancy. Of 312 eligible participants, 232 (74%) completed the questionnaire. In total, 196 COVID-19 vaccinations and 115 SARS-CoV-2 infections during pregnancy were reported. Infections were mostly first infections (86; 75%), caused by the Omicron variant (95; 83%), in women who had received ≥1 vaccination prior to infection (101; 88%). SARS-CoV-2 infection during pregnancy was not significantly associated with gestational age ( β = 1.7; 95%CI: -1.6-5.0), birth weight ( β = 82; -59 to 223), Apgar score <9 (odds ratio (OR): 1.3; 0.6-2.9), postpartum hospital stay (OR: 1.0; 0.6-1.8), or neonatal intensive care unit admission (OR: 0.8; 0.2-3.2). COVID-19 vaccination during pregnancy was not significantly associated with gestational age ( β = -0.4; -4.0 to 3.2), birth weight ( β = 88; -64 to 240), Apgar score <9 (OR: 0.9; 0.4-2.3), postpartum hospital stay (OR: 0.9; 0.5-1.7), or neonatal intensive care unit admission (OR: 1.6; 0.4-8.6). In conclusion, this study did not find an effect of SARS-CoV-2 infection or COVID-19 vaccination during pregnancy on any of the studied neonatal outcomes among a general Dutch, largely vaccinated, population. Together with data from other studies, this supports the safety of COVID-19 vaccination during pregnancy.

Background: Information on the magnitude and duration of antibody levels after COVID-19 vaccination in different groups may be useful for prioritizing of additional vaccinations., Methods: Serum samples were collected every six months in a prospective cohort study among adults in the Netherlands. Geometric mean concentrations (GMCs) of antibodies against the receptor binding domain of the SARS-CoV-2 spike protein were calculated after the primary series, first, and second booster vaccinations. Effects of age (18-59 vs 60-85 years) and medical risk conditions on GMC 2-6 weeks and 21-25 weeks after each vaccination, and on waning during 3-25 weeks after each vaccination, were estimated by linear regression., Results: We included 20,640, 15,229 and 8,392 samples collected after primary, first and second booster vaccination, respectively. GMCs at 2-6 and 21-25 weeks after primary series were lower in participants with older age or medical risk conditions. After the first booster, older age was associated with lower GMC at 2-6 weeks and at 21-25 weeks. Waning after the first and second boosters (only 60-85) was not associated with age or medical risk conditions., Conclusions: Since antibody differences by age and medical risk groups have become small with increasing number of doses, other factors such as COVID-19 disease severity rather than antibody levels are useful for prioritization of additional vaccinations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Purpose: VAccine Study COVID-19 (VASCO) is a cohort study with a 5-year follow-up that was initiated when COVID-19 vaccination was introduced in the Netherlands. The primary objective is to estimate real-world vaccine effectiveness (VE) of COVID-19 vaccines against SARS-CoV-2 infection in the Netherlands, overall and in four subpopulations defined by age and medical risk., Participants: The cohort consists of 45 547 community-dwelling participants aged 18-85 years who were included irrespective of their COVID-19 vaccination status or intention to get vaccinated. A medical risk condition is present in 4289 (19.8%) of 21 679 individuals aged 18-59 years, and in 9135 (38.3%) of 23 821 individuals aged 60-85 years. After 1 year of follow-up, 5502 participants had dropped out of the study. At inclusion and several times after inclusion, participants are asked to take a self-collected fingerprick blood sample in which nucleoprotein and spike protein receptor binding domain-specific antibody concentrations are assessed. Participants are also asked to complete monthly digital questionnaires in the first year, and 3 monthly in years 2-5, including questions on sociodemographic factors, health status, COVID-19 vaccination, SARS-CoV-2-related symptoms and testing results, and behavioural responses to COVID-19 measures., Findings to Date: VASCO data have been used to describe VE against SARS-CoV-2 infection of primary vaccination, first and second booster and bivalent boosters, the impact of hybrid immunity on SARS-CoV-2 infection and VE against infectiousness. Furthermore, data were used to describe antibody response following vaccination and breakthrough infections and to investigate the relation between antibody response and reactogenicity., Future Plans: VASCO will be able to contribute to policy decision-making regarding future COVID-19 vaccination. Furthermore, VASCO provides an infrastructure to conduct further studies and to respond to changes in vaccination campaigns and testing policy, and new virus variants., Trial Registration Number: NL9279., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

BackgroundNon-severe adverse events (AE) including pain at injection site or fever are common after COVID-19 vaccination.AimTo describe determinants of AE after COVID-19 vaccination and investigate the association between AE and pre- and post-vaccination antibody concentrations.MethodsParticipants of an ongoing prospective cohort study (VASCO) completed a questionnaire on AE within 2 months after vaccination and provided 6 monthly serum samples during May 2021-November 2022. Logistic regression analyses were performed to investigate AE determinants after mRNA vaccination, including pre-vaccination Ig antibody concentrations against the SARS-CoV-2 spike protein receptor binding domain. Multivariable linear regression was performed in SARS-CoV-2-naive participants to assess the association between AE and log-transformed antibody concentrations 3-8 weeks after mRNA vaccination.ResultsWe received 47,947 completed AE questionnaires by 28,032 participants. In 42% and 34% of questionnaires, injection site and systemic AE were reported, respectively. In 2.2% of questionnaires, participants sought medical attention. AE were reported more frequently by women, younger participants (< 60 years), participants with medical risk conditions and Spikevax recipients (vs Comirnaty). Higher pre-vaccination antibody concentrations were associated with higher incidence of systemic AE after the second and third dose, but not with injection site AE or AE for which medical attention was sought. Any AE after the third dose was associated with higher post-vaccination antibody concentrations (geometric mean concentration ratio: 1.38; 95% CI: 1.23-1.54).ConclusionsOur study suggests that high pre-vaccination antibody levels are associated with AE, and experiencing AE may be a marker for higher antibody response to vaccination.

Background: We aimed to estimate vaccine effectiveness against infection (VE-infection) and against further transmission (VE-infectiousness) in a household setting during Delta and Omicron. Knowing these effects can aid policy makers in deciding which groups to prioritize for vaccination., Methods: Participants with a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test were asked about coronavirus disease 2019 (COVID-19) vaccination status and SARS-CoV-2 testing of their household members 1 month later. VE-infection and VE-infectiousness were estimated using generalized estimating equation logistic regression adjusting for age, vaccination status, calendar week, and household size., Results: A total of 3399 questionnaires concerning 4105 household members were included. During the Delta period, VE-infection and VE-infectiousness of primary series were 47% (95% confidence interval [CI], -27% to 78%) and 70% (95% CI, 28% to 87%), respectively. During the Omicron period, VE-infection was -36% (95% CI, -88% to 1%) for primary series and -28% (95% CI, -77% to 7%) for booster vaccination. VE-infectiousness was 45% (95% CI, -14% to 74%) for primary series and 64% (95% CI, 31% to 82%) for booster vaccination., Conclusions: Our study shows that COVID-19 vaccination is effective against infection with SARS-CoV-2 Delta and against infectiousness of SARS-CoV-2 Delta and Omicron. Estimation of VE against infection with SARS-CoV-2 Omicron was limited by several factors. Our results support booster vaccination for those in close contact with vulnerable people to prevent transmission., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)