Safety Monitoring of COVID-19 mRNA Vaccine Second Booster Doses Among Adults Aged ≥50 Years - United States, March 29, 2022-July 10, 2022

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.

FIGURE

Adverse reactions and health impacts reported by adults aged ≥50 years who received COVID-19 vaccine booster, by dose — v-safe data, United States, March 29–July 10, 2022 * Local injection site reactions included itching, pain, redness, and swelling. Systemic reactions included abdominal pain, myalgia, chills, diarrhea, fatigue, fever, headache, joint pain, nausea, rash, and vomiting. Health impacts included inability to perform normal daily activities, inability to work or attend school, and receipt of medical care. ^† Adults received either homologous Moderna (125,807) or Pfizer-BioNTech (123,080) COVID-19 vaccine booster doses and completed at least one v-safe health check-in survey on days 0–7 after each vaccine dose. ^§ The odds of reporting any local injection site or systemic reaction or health impact after second booster dose and previous doses were compared using a multivariable generalized estimating equations model that accounted for the correlation between registrants and adjusted for demographic variables (p-values <0.05 were considered statistically significant); all second booster and first booster dose comparisons were statistically significant.