RICHMOND, Va. (WRIC) — Since the first COVID-19 vaccines were granted Emergency Use Authorization by the Food and Drug Administration (FDA), the Virginia Department of Health (VDH) has received 3,590,965 doses of the vaccine as of March 26, a combination of Moderna, Pfizer-BioNTech and Johnson & Johnson.

The latter requires one does, while the other two need two doses for full efficacy, which means how effective the vaccine is at preventing COVID-19. So which is the best vaccine for you? Why do some people experience side effects, while others do not? How does the COVID-19 vaccine work?

8News spoke with Dr. Michael Stevens, VCU Health Infectious Disease, to answer those questions.