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. 2022 Aug 1;182(8):825-831.
doi: 10.1001/jamainternmed.2022.2442.

Association of COVID-19 Vaccination During Pregnancy With Incidence of SARS-CoV-2 Infection in Infants

Ellen Øen Carlsen  1 , Maria C Magnus  1 , Laura Oakley  1   2 , Deshayne B Fell  3   4 , Margrethe Greve-Isdahl  5 , Jonas Minet Kinge  1   6 , Siri E Håberg  1
Affiliations

Association of COVID-19 Vaccination During Pregnancy With Incidence of SARS-CoV-2 Infection in Infants

Ellen Øen Carlsen et al. JAMA Intern Med. .

Abstract

Importance: Pregnant women are recommended to receive COVID-19 vaccination to reduce risk of severe COVID-19. Whether vaccination during pregnancy also provides passive protection to infants after birth remains unclear.

Objective: To determine whether COVID-19 vaccination in pregnancy was associated with reduced risk of COVID-19 in infants up to age 4 months during COVID-19 pandemic periods dominated by Delta and Omicron variants.

Design, setting, and participants: This nationwide, register-based cohort study included all live-born infants born in Norway between September 1, 2021, and February 28, 2022.

Exposures: Maternal messenger RNA COVID-19 vaccination during second or third trimester compared with no vaccination before or during pregnancy.

Main outcomes and measures: The risk of a positive polymerase chain reaction test result for SARS-CoV-2 during an infant's first 4 months of life by maternal vaccination status during pregnancy with either dose 2 or 3 was estimated, as stratified by periods dominated by the Delta variant (between September 1 and December 31, 2021) or Omicron variant (after January 1, 2022, to the end of follow-up on April 4, 2022). A Cox proportional hazard regression was used, adjusting for maternal age, parity, education, maternal country of birth, and county of residence.

Results: Of 21 643 live-born infants, 9739 (45.0%) were born to women who received a second or third dose of a COVID-19 vaccine during pregnancy. The first 4 months of life incidence rate of a positive test for SARS-CoV-2 was 5.8 per 10 000 follow-up days. Infants of mothers vaccinated during pregnancy had a lower risk of a positive test compared with infants of unvaccinated mothers and lower risk during the Delta variant-dominated period (incidence rate, 1.2 vs 3.0 per 10 000 follow-up days; adjusted hazard ratio, 0.29; 95% CI, 0.19-0.46) compared with the Omicron period (incidence rate, 7.0 vs 10.9 per 10 000 follow-up days; adjusted hazard ratio, 0.67; 95% CI, 0.57-0.79).

Conclusions and relevance: The results of this Norwegian population-based cohort study suggested a lower risk of a positive test for SARS-CoV-2 during the first 4 months of life among infants born to mothers who were vaccinated during pregnancy. Maternal COVID-19 vaccination may provide passive protection to young infants, for whom COVID-19 vaccines are currently not available.

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Conflict of interest statement

Conflict of Interest Disclosures: Drs Carlsen and Kinge reported grants from the Norwegian Research Council during the conduct of the study. Drs Magnus and Håberg reported grants from the Research Council of Norway and NordForsk during the conduct of the study. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Flowchart of Selection of Study Participants
Figure 2.
Figure 2.. Cumulative Proportion of Number of Infants With a Positive SARS-CoV-2 Polymerase Chain Reaction Test by Maternal COVID-19 Vaccination Status
A, Delta variant–dominated period: September 1 to December 31, 2021. B, Omicron variant–dominated period: January 1 to April 4, 2022. The shaded bands correspond to the 95% CIs.
See this image and copyright information in PMC

References

    1. Cui X, Zhao Z, Zhang T, et al. . A systematic review and meta-analysis of children with coronavirus disease 2019 (COVID-19). J Med Virol. 2021;93(2):1057-1069. doi:10.1002/jmv.26398 - DOI - PMC - PubMed
    1. Campbell H, Gupta S, Dolan GP, et al. . Review of vaccination in pregnancy to prevent pertussis in early infancy. J Med Microbiol. 2018;67(10):1426-1456. doi:10.1099/jmm.0.000829 - DOI - PubMed
    1. Regan AK, Munoz FM. Efficacy and safety of influenza vaccination during pregnancy: realizing the potential of maternal influenza immunization. Expert Rev Vaccines. 2021;20(6):649-660. doi:10.1080/14760584.2021.1915138 - DOI - PubMed
    1. Abu-Raya B, Madhi SA, Omer SB, et al. . Global perspectives on immunization against SARS-CoV-2 during pregnancy and priorities for future research: an international consensus paper from the World Association of Infectious Diseases and Immunological Disorders. Front Immunol. 2021;12:808064. doi:10.3389/fimmu.2021.808064 - DOI - PMC - PubMed
    1. Flannery DD, Gouma S, Dhudasia MB, et al. . Assessment of maternal and neonatal cord blood SARS-CoV-2 antibodies and placental transfer ratios. JAMA Pediatr. 2021;175(6):594-600. doi:10.1001/jamapediatrics.2021.0038 - DOI - PMC - PubMed

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