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. 2023 Jan 6;76(1):57-65.
doi: 10.1093/cid/ciac739.

Pregnancy Status at the Time of Coronavirus Disease 2019 Vaccination and Incidence of Severe Acute Respiratory Syndrome Coronavirus 2 Infection

Maria C Magnus  1 , Siri E Håberg  1 , Ellen Ø Carlsen  1 , Jeffrey C Kwong  2   3   4   5   6   7 , Sarah A Buchan  2   4 , Deshayne B Fell  8   9
Affiliations

Pregnancy Status at the Time of Coronavirus Disease 2019 Vaccination and Incidence of Severe Acute Respiratory Syndrome Coronavirus 2 Infection

Maria C Magnus et al. Clin Infect Dis. .

Abstract

Background: Pregnant women are recommended to receive coronavirus disease 2019 (COVID-19) vaccines; however, relative effectiveness of vaccination by pregnancy status is unclear.

Methods: We compared the relative effectiveness of messenger RNA (mRNA) COVID-19 vaccines according to whether women received both doses while pregnant (n = 7412), 1 dose while pregnant (n = 3538), both doses while postpartum (n = 1856), or both doses while neither pregnant nor postpartum (n = 6687). We estimated risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection starting 14 days after the second dose using Cox regression, reporting hazard ratios (HRs) and 95% confidence intervals (CIs). Second, we examined relative effectiveness of a third (booster) dose while pregnant compared to outside pregnancy. The major circulating variant during the study period was the Delta variant.

Results: Fifty-four percent of women received 2 doses of the BNT162b2 vaccine, 16% received 2 doses of the mRNA-1273 vaccine, while 30% received 1 dose of both vaccines. Compared to women who received both doses while neither pregnant nor postpartum, the adjusted HR for a positive SARS-CoV-2 polymerase chain reaction test was similar if the woman received both doses while pregnant (1.04 [95% CI, .94-1.17]), 1 dose while pregnant and 1 dose before or after pregnancy (1.03 [95% CI, .93-1.14]), or both doses while postpartum (0.99 [95% CI, .92-1.07]). The findings were similar for BNT162b2 (Pfizer-BioNTech Comirnaty) and mRNA-1273 (Moderna Spikevax), and during Delta- and Omicron-dominant periods. We observed no differences in the relative effectiveness of the booster dose according to pregnancy status.

Conclusions: We observed similar effectiveness of mRNA vaccines against SARS-CoV-2 infection among women regardless of pregnancy status at the time of vaccination.

Keywords: COVID-19; postpartum; pregnancy; vaccination.

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Conflict of interest statement

Potential conflicts of interest. S. B., D. B. F., and J. C. K. report co-investigator grants for COVID-19 vaccine monitoring in pregnancy in Ontario, Canada, from the COVID-19 Immunity Task Force, Public Health Agency of Canada. E. O. C. reports grants or contracts from the Norwegian Research Council. D. B. F. reports travel support to present on COVID-19 vaccine safety during pregnancy at the World Vaccine Congress, Washington, D.C., April 2022, and a Liaison Member of Canada's National Advisory Committee on Immunization. All other authors report no potential 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.

Figures

Figure 1.
Figure 1.
Calendar date of administration of the second messenger RNA coronavirus disease 2019 vaccine according to pregnancy status at the time of vaccination.
Figure 2.
Figure 2.
Cumulative incidence of severe acute respiratory syndrome coronavirus 2 infection ≥14 days after the second dose of a messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccine according to pregnancy status at the time of vaccination. The time axis reflects the number of days counting from 14 days after the second dose of an mRNA COVID-19 vaccine was administered.
Figure 3.
Figure 3.
Cumulative incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection ≥14 days after the booster dose of a messenger RNA (mRNA) coronavirus disease 2019 vaccine according to pregnancy status at the time of vaccination. The time axis reflects the number of days from 14 days after the booster (third) vaccine dose of an mRNA vaccine against SARS-CoV-2 was administered.
See this image and copyright information in PMC

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