Safety of Simultaneous Administration of Bivalent mRNA COVID-19 and Influenza Vaccines in the Vaccine Adverse Event Reporting System (VAERS)

Introduction Bivalent mRNA coronavirus disease 2019 (COVID-19) vaccines may be simultaneously administered with other recommended vaccines, including seasonal influenza vaccines. However, few studies have evaluated the safety of co-administration of bivalent mRNA COVID-19 and seasonal influenza vaccines. Objective The aim was to describe reports to the Vaccine Adverse Event Reporting System (VAERS) after co-administration of bivalent mRNA COVID-19 and seasonal influenza vaccines. Methods We searched the VAERS database for reports of adverse events (AEs) following co-administration of bivalent mRNA COVID-19 and seasonal influenza vaccines during the period of September 1, 2022–March 31, 2023. We assessed the characteristics of these reports and described the most frequently reported AEs. Clinicians reviewed available medical records for reports of serious AEs and adverse events of special interest (AESI). Results During the period of 1 September 2022 through 31 March 2023, VAERS received 3689 reports of AEs following co-administration of bivalent mRNA COVID-19 and seasonal influenza vaccines. The median age of vaccinees was 59 years (interquartile range 39, 70 years); 342 reports (9.3%) were classified as serious. The most common AEs among non-serious reports were severe-acute-respiratory-syndrome-related coronavirus (SARS-CoV-2) infection (785, 23.5%), cough (592, 17.7%), and fatigue (568, 17.0%). The most common AEs among serious reports were Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection (88, 25.7%), dyspnea (81, 23.7%), and condition aggravated (55, 16.1%). Discussion Reports of AEs following co-administration of bivalent 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) was expected due to Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) reporting requirements. CDC and FDA will continue to monitor the safety of co-administration of mRNA COVID-19 and seasonal influenza vaccines.