Evaluating COVID-19 vaccine effectiveness during pre-Delta, Delta and Omicron dominant periods among pregnant people in the U.S.: Retrospective cohort analysis from a nationally sampled cohort in National COVID Collaborative Cohort (N3C)

Affiliations

¹ Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA.
² Biostatistics Program / Office of Clinical Research Support, Office of the Director, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
³ Office of Data Science and Emerging Technologies, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA.
⁴ Palantir Technologies, Denver, CO, USA.
⁵ College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.
⁶ Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
⁷ Department of Neurological Sciences, College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Great Plains IDeA-CTR, Omaha, NE, USA.
⁸ IPQ Analytics, LLC, Kennett Square, PA, USA.
⁹ Beaumont Hospital-Dearborn, Dearborn, MI, USA.
¹⁰ University of Minnesota School of Public Health, Minneapolis, MN, USA.
¹¹ Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA.
¹² Department of Medicine and Global Health, University of Washington, Seattle, WA, USA.
¹³ Departments of Medicine and Public Health, University of Alabama Birmingham, Birmingham, AL, USA.

PMID: 39363958
PMCID: PMC11449158
DOI: 10.1136/bmjph-2023-000770

Evaluating COVID-19 vaccine effectiveness during pre-Delta, Delta and Omicron dominant periods among pregnant people in the U.S.: Retrospective cohort analysis from a nationally sampled cohort in National COVID Collaborative Cohort (N3C)

Qiuyuan Crystal Qin et al. BMJ Public Health. 2024 Jul.

. 2024 Jul;2(1):e000770.

doi: 10.1136/bmjph-2023-000770. Epub 2024 Jun 3.

Authors

Affiliations

¹ Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA.
² Biostatistics Program / Office of Clinical Research Support, Office of the Director, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
³ Office of Data Science and Emerging Technologies, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA.
⁴ Palantir Technologies, Denver, CO, USA.
⁵ College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.
⁶ Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
⁷ Department of Neurological Sciences, College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Great Plains IDeA-CTR, Omaha, NE, USA.
⁸ IPQ Analytics, LLC, Kennett Square, PA, USA.
⁹ Beaumont Hospital-Dearborn, Dearborn, MI, USA.
¹⁰ University of Minnesota School of Public Health, Minneapolis, MN, USA.
¹¹ Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA.
¹² Department of Medicine and Global Health, University of Washington, Seattle, WA, USA.
¹³ Departments of Medicine and Public Health, University of Alabama Birmingham, Birmingham, AL, USA.

PMID: 39363958
PMCID: PMC11449158
DOI: 10.1136/bmjph-2023-000770

Abstract

Objectives: To evaluate the effectiveness of COVID-19 vaccinations (initial and booster) during pre-Delta, Delta, and Omicron dominant periods among pregnant people via (1) COVID-19 incident and severe infections among pregnant people who were vaccinated vs. unvaccinated and (2) post-COVID-19 vaccination breakthrough infections and severe infections among vaccinated females who were pregnant vs. non-pregnant.

Design: Retrospective cohort study using nationally sampled electronic health records data from the National COVID Cohort Collaborative (N3C), December 10, 2020, to June 07, 2022.

Participants: Cohort 1 included pregnant people (15-55 years), and Cohort 2 included vaccinated females of reproductive age (15-55 years).

Exposures: (1) COVID-19 vaccination and (2) pregnancy.

Main outcome measures: Adjusted hazard ratios (aHRs) for COVID-19 incident or breakthrough infections and severe infections (i.e., COVID-19 infections with related hospitalizations).

Results: In Cohort 1, 301,107 pregnant people were included. Compared to unvaccinated pregnant people, the aHRs for pregnant people with initial vaccinations during pregnancy of incident COVID-19 were 0.77 (95% CI: 0.62, 0.96) and 0.88 (95%CI: 0.73, 1.07) and aHRs of severe COVID-19 infections were 0.65 (95% CI: 0.47, 0.90) and 0.79 (95% CI: 0.51, 1.21) during the Delta and Omicron periods, respectively. Compared to pregnant people with full initial vaccinations, the aHR of incident COVID-19 for pregnant people with booster vaccinations was 0.64 (95% CI: 0.58, 0.71) during the Omicron period. In Cohort 2, 934,337 vaccinated people were included. Compared to vaccinated non-pregnant females, the aHRs of severe COVID-19 infections for people with initial vaccinations during pregnancy was 2.71 (95% CI: 1.31, 5.60) during the Omicron periods.

Conclusions: Pregnant people with initial and booster vaccinations during pregnancy had a lower risk of incident and severe COVID-19 infections compared to unvaccinated pregnant people across the pandemic stages. However, vaccinated pregnant people still had a higher risk of severe infections compared to non-pregnant females.

Keywords: COVID-19 pandemic; pregnant people; vaccine effectiveness.

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Conflict of interest statement

Conflicts of Interest and Disclaimers APC helped to conceptualize this study while at Vanderbilt University. Following this contribution, APC joined the staff of AstraZeneca Pharmaceuticals, LP (“AZ”), which markets a COVID-19 vaccine in direct competition to other products considered in this manuscript. After joining AZ, APC did not participate in the conduct of this research, with his subsequent contributions limited to ad hoc consultation on methods for real-world data management, as part of routine meetings of the N3C Pregnancy Domain Team for which he is an advisor. APC did not provide any guidance on product-specific or advocacy topics. Similarly, AZ did not provide any data, funding, or scientific input towards the results herein. The content is solely the responsibility of the authors and does not represent the official views of the National Institutes of Health, AZ, or the N3C program.

Figures

**Figure 1. Flow chart of analytic cohorts selection from the N3C cohort**

See this image and copyright information in PMC

References

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Evaluating COVID-19 vaccine effectiveness during pre-Delta, Delta and Omicron dominant periods among pregnant people in the U.S.: Retrospective cohort analysis from a nationally sampled cohort in National COVID Collaborative Cohort (N3C)

Affiliations

Evaluating COVID-19 vaccine effectiveness during pre-Delta, Delta and Omicron dominant periods among pregnant people in the U.S.: Retrospective cohort analysis from a nationally sampled cohort in National COVID Collaborative Cohort (N3C)

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

Grants and funding

LinkOut - more resources

Full Text Sources