COVID-19 Vaccine Effectiveness in Pregnant Women and their Infants

Abstract: Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) which emerged in December 2019 and has since led to an unprecedented global pandemic with high morbidity and mortality. Current authorized vaccines against SARS-CoV-2 demonstrated 70 - 95% efficacy in clinical trials, but the pivotal efficacy trials on which the emergency use authorizations are based did not include pregnant women. Thus, in the midst of a massive vaccination campaign, COVID-19 vaccine effectiveness in pregnant women and their infants is unknown. Pregnant women are at increased risk of COVID-19 infection and hospitalization, but currently there is no strong recommendation for or against COVID-19 vaccination during pregnancy. Additionally, COVID-19 vaccine uptake among pregnant women and factors associated with being vaccinated or unvaccinated are unknown. We propose to 1) estimate COVID-19 vaccine effectiveness for preventing laboratory-confirmed COVID-19 infection or COVID-19 hospitalization in pregnant women, 2) determine effectiveness of COVID-19 vaccination during pregnancy in preventing COVID-19 infection or hospitalization among infants during the first year of life; and determine whether effectiveness varies by trimester of vaccination and 3) estimate COVID-19 vaccination rates among pregnant women over time and among unvaccinated pregnant women, identify sociodemographic, geographic clusters and healthcare utilization patterns associated with being unvaccinated. We are well-positioned at Kaiser Permanente Northern California, a large integrated healthcare system with stable, diverse membership and comprehensive longitudinal electronic health records (EHR), to address the research aims. By using EHR data, the study will be cost effective and timely; providing information on COVID- 19 vaccine effectiveness among pregnant women and assessing whether maternal vaccination provides protection for their infants who are currently ineligible to receive COVID-19 vaccine. The proposed research can lead to evidence-based recommendations regarding COVID-19 vaccination in pregnant women and will provide critical information regarding characteristics of unvaccinated pregnant women that will be necessary for future development of targeted interventions to improve vaccine coverage among pregnant women.