V-safe: Summary of findings reported after COVID-19 vaccination to a US CDC active safety surveillance system through...

V-safe is an active surveillance system developed during the pandemic to monitor COVID-19 vaccine safety. After vaccination, US residents could enroll to receive text messages linked to health check-in surveys. Questions about symptoms and health impacts, including inability to complete daily activities, attend work or school, or receipt of medical care were asked at daily, weekly, and monthly intervals after vaccination. We describe demographics of participants compared to the vaccinated population, trends in enrollment, participation over time, and self-reported health impacts in the V-safe population during the COVID-19 pandemic. During December 14, 2020 - June 30, 2023, 9,609,282 persons completed at least one V-safe survey. Most were female (62.2%), aged 25-64 years (69.2%), and received an mRNA vaccine (95.0%). Compared to the US vaccinated population, a higher proportion of participants were non-Hispanic White or Asian and ≥ 75 years. Most registered for V-safe within the first few months after vaccination was recommended for their age group. Most completed an initial health survey within the first week after vaccination. Participation decreased for successive doses, especially among persons aged <18 years. Health impacts were reported more frequently during the first week post-vaccination, after dose 2 compared to dose 1, and among recipients of mRNA-1273 vaccine compared to recipients of BNT162b2 vaccine. Health impacts among children <12 years were reported slightly less frequently compared to adults. Seeking medical care was reported in the first week after vaccination by 0.8-1.2% of adults after doses 1-6 of an mRNA vaccine. Findings were similar to those in previous V-safe analyses and data from clinical trials. Rapidly decreasing participation during the course of the pandemic suggests that incentives encouraging survey completion in V-safe could be useful for improving safety monitoring for future emergency vaccines. V-safe continues to collect data about COVID-19 vaccines, with an emphasis on new products.