BACKGROUND: On June 8, 2021, a new 20-valent pneumococcal conjugate vaccine (PCV20, PREVNAR 20(®), Pfizer, Inc.) was licensed for use in adults aged ≥ 18 years by the US Food and Drug Administration (FDA). OBJECTIVE: To describe reports to the Vaccine Adverse Event Reporting System (VAERS) after administration of the 20-valent pneumococcal conjugate vaccine in adults. METHODS: We searched the VAERS for reports of adverse events involving persons aged ≥ 19 years who received PCV20 during October 20, 2021, through December 31, 2023. Our evaluation included automated analysis of reports, clinical review of serious reports and pre-specified events of special interest, empirical Bayesian data mining to assess for disproportionate reporting, and estimation of reporting rates for reports of Guillain-Barré syndrome (GBS). RESULTS: The VAERS received 1976 reports after PCV20 administration in persons aged ≥ 19 years (6% of reports involved serious events). The most common adverse events among persons aged 19-64 years (n = 798) were injection-site reactions (231, 29%), pain (134, 17%), erythema (118, 15%), and fever (117, 15%). For persons aged ≥ 65 years (n = 1178), the most common adverse events were injection-site reactions (417, 35%), pain (180, 15%), pain in extremity (162, 14%), and erythema (158, 13%). A data mining alert (EB05 = 3.812) for the MedDRA Preferred Term "Guillain-Barre syndrome" was observed for serious reports. Clinical review verified 11 of 20 GBS reports; 7/11 vaccine recipients were aged ≥ 65 years. Among the 11 verified cases, the median time from vaccination to symptom onset was 14 days. Five persons received another vaccine on the same visit. The reporting rate of GBS after PCV20 receipt was 0.5 cases per million doses distributed. No other safety concern was identified. CONCLUSIONS: During the period of this post-licensure review of PCV20, we found most reports were non-serious and comprised mostly local and systemic (e.g., fever) reactions consistent with prelicensure studies. In serious reports, we also identified a data mining alert for GBS after receipt of PCV20, which Centers for Disease Control and Prevention and the FDA are investigating further. No other new or unexpected safety concern was identified.

BACKGROUND: COVID-19 vaccines may be co-administered with other recommended vaccines, including seasonal influenza vaccines. However, few studies have evaluated the safety of co-administration of mRNA COVID-19 and seasonal influenza vaccines. OBJECTIVE: To describe reports to the Vaccine Adverse Event Reporting System (VAERS) after co-administration of mRNA COVID-19 and seasonal influenza vaccines. METHODS: We searched the VAERS database for reports of adverse events (AEs) following co-administration of mRNA COVID-19 and seasonal influenza vaccines and following a first booster dose mRNA COVID-19 vaccine alone, during July 1, 2021-June 30, 2022. We assessed the characteristics of these reports and described the most frequently reported MedDRA preferred terms (PTs). Clinicians reviewed available medical records for serious reports and reports of adverse events of special interest (AESI) and categorized the main diagnosis by system organ class. RESULTS: From July 1, 2021 through June 30, 2022, VAERS received 2,449 reports of adverse events following co-administration of mRNA COVID-19 and seasonal influenza vaccines. Median age of vaccinees was 48 years (IQR: 31, 66); 387 (15.8%) were classified as serious. Most reports (1,713; 69.3%) described co-administration of a first booster dose of an mRNA COVID-19 vaccine with seasonal influenza vaccine. The most common AEs among non-serious reports were injection site reactions (193; 14.5%), headache (181; 13.6%), and pain (171; 12.8%). The most common AEs among reports classified as serious were dyspnea (38; 14.9%), COVID-19 infection (32; 12.6%), and chest pain (27; 10.6%). DISCUSSION: This review of reports to VAERS following co-administration of mRNA COVID-19 and seasonal influenza vaccines did not reveal any unusual or unexpected patterns of AEs. Increased reporting of certain events (e.g., COVID-19 disease) was expected. CDC will continue to monitor the safety of co-administration of mRNA COVID-19 and seasonal influenza vaccines, including co-administration involving bivalent mRNA COVID-19 booster vaccines that have been recommended for people ages ≥ 6 months in the United States.