ABSTRACTBACKGROUNDAmong the various driving factors for vaccine hesitancy, confidence in the safety associated with the vaccine constitutes as one of the key factors. This study aimed at comparing the adverse effects of COVID-19 vaccines with the Flu vaccines.METHODSThe VAERS data from 01/01/2020 to 08/20/2021 were used. The MedDRA terms coded by VAERS were further aggregated by a clinician into clinically meaningful broader terms.RESULTSVarious common adverse events between Flu and COVID-19 vaccines have been identified. Adverse events such as headache and fever were very common across all age groups. Among the common adverse events between Flu and COVID-19 vaccine, the relative risk along with 95% CI indicated that such common adverse events were more likely to be experienced by COVID-19 vaccine users than Flu vaccine users. Our study also quantified the proportion of rare adverse events such as Guillain Barre Syndrome and Gynecological changes in the VAERS database for COVID-19 vaccines.CONCLUSIONSBased on the available data and results, it appears that there were some common adverse events between Flu vaccines and COVID-19 vaccines. These identified common adverse events warrant further investigations based on the relative risk and 95% CI.