(A-356) Safety Profile of Vaxzevria® COVID-19 Vaccine in the COVID-19 Vaccines International Pregnancy Exposure Registry (C-VIPER)

Background: COVID-19 vaccines are administered during pregnancy; however, scientific evidence regarding their safety in pregnant women and their offspring is limited. The goal of the C-VIPER post authorization study was to generate data on the safety of COVID-19 vaccines in pregnant women and the potential effects on their offspring.

Objectives: To describe pregnancy outcomes (obstetric, neonatal, and infant) of women exposed to >1 dose of Vaxzevria® vaccine.

Methods: The C-VIPER is an international, prospective, observational cohort study of consenting women (18+ years) exposed to ≥1 vaccine dose from 30 days preconception to end of pregnancy. Data for Vaxzevria were obtained between 26/03/21-15/12/23 using structured questionnaires supplemented by medical records when available. Information on maternal baseline characteristics, vaccine exposure (number/timing of doses), and risk factors were provided by women at enrollment. Additional data, including pregnancy outcomes, were collected monthly up to 12 months post-delivery or end of pregnancy. Liveborn infants were followed from birth up to 1 year of age, with data collected from mothers at birth and every 3 months thereafter. Independent adjudication and validation of adverse outcomes, including serious adverse events, were conducted. Data were summarized using descriptive statistics for the overall cohort and stratified by exposure to a single (homologous Vaxzevria® only) or mixed (heterologous) vaccination primary series.

Results: The analytic cohort consisted of 712 participants, with 605 (85.0%) in the homologous cohort and 107 (15.0%) in the heterologous cohort. The mean (SD) age at enrollment was 30.7 (5.6) and 33.3 (4.2) years, respectively. Pregnancy outcome data were available for 400/605 (66.1%) homologous and 98/107 (69.9%) heterologous participants, with 382 (95.5%) and 94 (95.9%) live births reported, respectively. The primary outcome, major congenital malformations (MCMs) in live births following maternal exposure either pre-pregnancy or during the first trimester, was observed in 7 out of 292 (2.4%) in the homologous cohort and 5 out of 81 (6.2%) in the heterologous cohort. The number of minor CMs was 15 (5.1%) and 6 (6.2%), respectively. There was no discernable pattern in the number or type of other secondary outcomes overall or by exposure cohort (data to be presented).

Conclusions: The C-VIPER study provides key information on MCMs and pregnancy outcomes, that pregnant women and their healthcare providers can consider when making an informed decision about COVID-19 vaccination during pregnancy. Based on the data collected, no safety concerns were identified for the C-VIPER participants who received Vaxzevria® or for their offspring.