Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Nov 1;6(11):e2342475.
doi: 10.1001/jamanetworkopen.2023.42475.

mRNA SARS-CoV-2 Vaccination Before vs During Pregnancy and Omicron Infection Among Infants

Orlanda Goh  1   2   3 , Deanette Pang  4 , Janice Tan  4 , David Lye  5   6   7   8 , Chia Yin Chong  5   7   9   10   11 , Benjamin Ong  4   7 , Kelvin Bryan Tan  4   11   12 , Chee Fu Yung  5   9   10   11
Affiliations

mRNA SARS-CoV-2 Vaccination Before vs During Pregnancy and Omicron Infection Among Infants

Orlanda Goh et al. JAMA Netw Open. .

Abstract

Importance: Infants younger than 6 months are at risk of severe SARS-CoV-2 infection. Data are lacking on the optimum timing for maternal vaccination and estimated effectiveness against Omicron variants, including XBB, for infants.

Objective: To investigate maternal vaccination against Omicron variants, including XBB, and the association of vaccination timing during pregnancy vs prior to pregnancy and risks of SARS-CoV-2 infection among infants aged 6 months or younger.

Design, setting, and participants: This population-based cohort study was conducted between January 1, 2022, and March 31, 2023. Singapore's national dataset was used to study infants born at greater than 32 weeks' gestation between January 1, 2022, and September 30, 2022. The study included infants whose parents had a confirmed SARS-CoV-2 infection from the date of birth up to 6 months of age. Of 21 609 infants born during this period, 7292 (33.7%) had at least 1 parent infected with SARS-CoV-2 before the age of 7 months. Statistical analysis was performed from April to July 2023.

Exposure: Infants' mothers were unvaccinated, vaccinated prior to pregnancy, or vaccinated with a messenger RNA (mRNA) SARS-CoV-2 vaccine during pregnancy.

Main outcome and measure: Infants were considered infected if they had a positive polymerase chain reaction test.

Results: Among 7292 infants included in this study, 4522 (62.0%) had mothers who were Chinese, 527 (7.2%) had mothers who were Indian, 2007 (27.5%) had mothers who were Malay, and 236 (3.2%) had mothers who were other ethnicity; 6809 infants (93.4%) were born at full term, and 1272 infants (17.4%) were infected during the study period. There were 7120 infants (97.6%) born to mothers who had been fully vaccinated or boosted as of 14 days prior to delivery. The crude incidence rate was 174.3 per 100 000 person-days among infants born to mothers who were unvaccinated, 122.2 per 100 000 person-days among infants born to mothers who were vaccinated before pregnancy, and 128.5 per 100 000 person-days among infants born to mothers who were vaccinated during pregnancy. The estimated vaccine effectiveness (VE) was 41.5% (95% CI, 22.8% to 55.7%) among infants born to mothers vaccinated during pregnancy. Infants of mothers who received vaccination prior to pregnancy did not have a lower risk for infection (estimated VE, 15.4% [95% CI, -17.6% to 39.1%]). A lower risk for Omicron XBB infection was only observed among mothers vaccinated with the third (booster) dose antenatally (estimated VE, 76.7% [95% CI, 12.8% to 93.8%]).

Conclusions and relevance: In this population-based cohort study, maternal mRNA vaccination was associated with a lower risk of Omicron SARS-CoV-2 infection among infants up to 6 months of age only if the vaccine was given during the antenatal period. These findings suggest that mRNA vaccination during pregnancy may be needed for lower risk of SARS-CoV-2 infection among newborns.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest Disclosures: Dr Yung reported funding to attend conferences and honorarium from Sanofi, Pfizer, and Takeda, outside of the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Inclusion and Exclusion Criteria
mRNA indicates messenger RNA.
Figure 2.
Figure 2.. Cumulative Proportion of Infants With SARS-CoV-2 Infection by Maternal Vaccination Status
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. Hobbs CV, Woodworth K, Young CC, et al. ; for the Overcoming COVID-19 Investigators . Frequency, characteristics and complications of COVID-19 in hospitalized infants. Pediatr Infect Dis J. 2022;41(3):e81-e86. doi:10.1097/INF.0000000000003435 - DOI - PMC - PubMed
    1. Marks KJ, Whitaker M, Agathis NT, et al. ; COVID-NET Surveillance Team . Hospitalization of infants and children aged 0-4 years with laboratory-confirmed COVID-19 - COVID-NET, 14 states, March 2020-February 2022. MMWR Morb Mortal Wkly Rep. 2022;71(11):429-436. doi:10.15585/mmwr.mm7111e2 - DOI - PMC - PubMed
    1. Tan SHX, Cook AR, Heng D, Ong B, Lye DC, Tan KB. . Effectiveness of BNT162b2 vaccine against Omicron in children 5 to 11 years of age. N Engl J Med. 2022;387(6):525-532. doi:10.1056/NEJMoa2203209 - DOI - PMC - PubMed
    1. Walter EB, Talaat KR, Sabharwal C, et al. ; C4591007 Clinical Trial Group . Evaluation of the BNT162b2 Covid-19 vaccine in children 5 to 11 years of age. N Engl J Med. 2022;386(1):35-46. doi:10.1056/NEJMoa2116298 - DOI - PMC - PubMed

Publication types

Supplementary concepts