Safety Monitoring of COVID-19 mRNA Vaccine Second Booster Doses Among Adults Aged ≥50 Years — United States, March 29, 2022–July 10, 2022
Anne M. Hause, James Baggs, Paige Marquez, Winston E. Abara, Jane Baumblatt, Phillip G. Blanc, John R. Su, Brandon Hugueley, Casey Parker, Tanya R. Myers, Julianne Gee, Tom T. Shimabukuro, David K. Shay
Abstract
The Advisory Committee on Immunization Practices (ACIP) recommends that all persons aged 5 years receive 1 booster dose of a COVID-19 vaccine after completion of their primary series.* On March 29, 2022, the Food and Drug Administration (FDA) authorized a second mRNA booster dose 4 months after receipt of a first booster dose for adults aged 50 years and persons aged 12 years with moderate to severe immunocompromise (1,2). To characterize the safety of a second mRNA booster dose among persons aged 50 years, CDC reviewed adverse events and health impact assessments reported to v-safe and the Vaccine Adverse Event Reporting System (VAERS) after receipt of a second mRNA booster dose during March 29-July 10, 2022. V-safe is a voluntary smartphone-based U.S. active surveillance system that monitors adverse events occurring after COVID-19 vaccination. VAERS is a U.S. passive surveillance system for monitoring adverse events after vaccination, managed by CDC and FDA (3). During March 29-July 10, 2022, approximately 16.8 million persons in the United States aged 50 years received a fourth dose. Among 286,380 v-safe registrants aged 50 years who reported receiving a second booster of an mRNA vaccine, 86.9% received vaccines from the same manufacturer for all 4 doses (i.e., homologous vaccination). Among registrants who reported homologous vaccination, injection site and systemic reactions were less frequent after the second booster dose than after the first booster dose. VAERS received 8,515 reports of adverse events after second mRNA booster doses among adults aged 50 years, including 8,073 (94.8%) nonserious and 442 (5.1%) serious events. CDC recommends that health care providers and patients be advised that local and systemic reactions are expected after a second booster dose, and that serious adverse events are uncommon.