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)

• Published in: BMJ Public Health Vol. 2; no. 1; p. e000770
• Main Authors: Wilkins, Kenneth, Jones, Sara E, Sun, Jing, Anzalone, Jerrod, Zheng, Qulu, Liebman, Michael, Groene Faherty, Emily A, Hill, Elaine, Patel, Rena C, Wilcox, Adam B, Lee, Adam M, Manna, Amin, Zhou, Andrea, Southerland, Andrew, Girvin, Andrew T, Walden, Anita, Sharathkumar, Anjali A, Bates, Benjamin, Hendricks, Brian, Patel, Brijesh, Signore, Caroline, Bramante, Carolyn, Ward-Caviness, Cavin, Madlock-Brown, Charisse, Suver, Christine, Chute, Christopher, Dillon, Christopher, Takemoto, Cliff, Gabriel, Davera, Eichmann, David A, Mazzotti, Diego, Zampino, Elizabeth, Marti, Emily Carlson, Pfaff, Emily R, French, Evan, Koraishy, Farrukh M, Prior, Fred, Sokos, George, Martin, Greg, Mehta, Hemalkumar, Liu, Hongfang, Sidky, Hythem, Awori Hayanga, JW, Harper, Jeremy Richard, Islam, Jessica, Ge, Jin, Gagnier, Joel, Saltz, Joel H, Saltz, Joel, Buse, John, Mathew, Jomol, Rutter, Joni L, McMurry, Julie A, Guinney, Justin, Starren, Justin, Crowley, Karen, Walters, Kellie M, Wilkins, Ken, Cato, Kenrick Dwain, Northington, Lavance, Pyles, Lee Allan, Misquitta, Leonie, Cottrell, Lesley, Bissell, Mark M, Clark, Marshall, Emmett, Mary, Saltz, Mary Morrison, Palchuk, Matvey B, Haendel, Melissa A, Adams, Meredith, Temple-O'Connor, Meredith, Kurilla, Michael G, Qureshi, Nabeel, Garbarini, Nicole, Sadan, Ofer, Francis, Patricia A, Burgoon, Penny Wung, Payne, Philip RO, Fuentes, Rafael, Jawa, Randeep, Erwin-Cohen, Rebecca, Moffitt, Richard A, Zhu, Richard L, Kamaleswaran, Rishi, Hurley, Robert, Miller, Robert T, Michael, Sam G, Chapman, Scott, Shawn, T, O'Neil, Soko Setoguchi, Hong, Stephanie S, Johnson, Steve, Bennett, Tellen D, Callahan, Tiffany, Sheikh, Usman, Subbian, Vignesh, Beasley, Will, Cooper, Will, Hillegass, William, Zhang, Xiaohan Tanner
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 01-07-2024; BMJ Publishing Group
• Subjects: COVID-19; Female; Original research; Preventive Medicine; vaccine effectiveness; COVID-19 pandemic; pregnant people
• ISSN: 2753-4294; 2753-4294
• DOI: 10.1136/bmjph-2023-000770

ObjectivesTo 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 versus unvaccinated and (2) post-COVID-19 vaccination breakthrough infections and severe infections among vaccinated females who were pregnant versus non-pregnant.DesignRetrospective cohort study using nationally sampled electronic health records data from the National COVID Cohort Collaborative, 10 December 2020 –7 June 2022.ParticipantsCohort 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 measuresAdjusted HRs (aHRs) for COVID-19 incident or breakthrough infections and severe infections (ie, COVID-19 infections with related hospitalisations).ResultsIn cohort 1, 301 107 pregnant people were included. Compared with unvaccinated pregnant people, the aHRs for pregnant people with initial vaccinations during pregnancy of incident COVID-19 were 0.77 (95% CI 0.62 to 0.96) and 0.88 (95% CI 0.73 to 1.07) and aHRs of severe COVID-19 infections were 0.65 (95% CI 0.47 to 0.90) and 0.79 (95% CI 0.51 to 1.21) during the Delta and Omicron periods, respectively. Compared with 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 to 0.71) during the Omicron period. In cohort 2, 934 337 vaccinated people were included. Compared with 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 to 5.60) during the Omicron periods.ConclusionsPregnant people with initial and booster vaccinations during pregnancy had a lower risk of incident and severe COVID-19 infections compared with unvaccinated pregnant people across the pandemic stages. However, vaccinated pregnant people still had a higher risk of severe infections compared with non-pregnant females.