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Publications

Journal Article Research Support, Non-U.S. Gov't Ppublish 96 citations

PubMed: 35648413 DOI: 10.1001/jamainternmed.2022.2442

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

JAMA Intern Med 182(8):825-831

Authors: Ellen Øen Carlsen, Maria C Magnus, Laura Oakley, Deshayne B Fell, Margrethe Greve-Isdahl, Jonas Minet Kinge, Siri E Håberg

Affiliations

  • Centre for Fertility and Health, Norwegian Institute of Public Health, Oslo, Norway.
  • Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, England.
  • School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada.
  • Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
  • Department of Infectious Disease, Norwegian Institute of Public Health, Oslo, Norway.
  • Department of Health Management and Health Economics, Institute of Health and Society, University of Oslo, Oslo, Norway.

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.

MeSH

Pregnancy, Sars-Cov-2, Mothers, Parturition, Vaccines, Incidence, Covid-19 Vaccines, Internal Medicine, Cohort Studies, Vaccination, Covid-19, Severe Acute Respiratory Syndrome-Related Coronavirus, Infections, Infant

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