Introduction: Novel coronavirus disease (COVID-19) is a worldwide epidemic that severely affected healthcare systems and tested their preparedness. There is a current controversy over the safety profile of the approved COVID-19 vaccines and their association with severe and possibly lethal adverse effects (A.E.s).

Objective: To evaluate and compare the number of adverse effects reported to the Vaccine Adverse Event Reporting System (VAERS) for both COVID-19 and influenza vaccines. In addition, we will identify the most common adverse effects for each vaccine.

Methods: This retrospective descriptive study was conducted to compare the frequency and outcomes of using COVID-19 and flu vaccines among the U.S. population. Details of the U.S. Post-Marketing Surveillance reports (from December 2020 to December 2021) of both vaccines were retrieved from the U.S. Vaccine Adverse Event Reporting System (VAERS). Data analyses were performed using Excel and SAS 9.4 software.

Results: A total of 544,025 reports for COVID-19 vaccines and 15,871 reports post-flu-vaccines administrations were reported to VAERS. Compared to males, females accounted for more than 58% of flu-vaccine reported A.E.s and nearly 70% of all types of COVID-19 vaccines. The estimated incidence of A.E.s associated with COVID-19 vaccines in the U.S. was 1.14 per 1000 persons; while for those who used flu vaccines the estimated incidence was 0.04 per 1000 persons.

Conclusion: The incidence of A.E.s among COVID-19 recipients was remarkably high compared to that of flu-vaccine recipients. Mortality and life-threatening situations post COVID-19 vaccines were 2-folds that of flu-vaccine patients. However, most of the reported A.E.s were similar between both vaccines in terms of symptoms reported.