While both vaccines are over 94% effective, their clinical trials have been slightly different. Pfizer’s vaccine prevented coronavirus in all but eight of the 18,198 study participants who were tracked for about two months after receiving the second dose of the vaccine. With the Moderna vaccine, on the other hand, five of the 13,934 study participants developed coronavirus after being tracked for about seven weeks after their second dose. Vaccines from both companies have been effective in older adults, but Moderna was 100% effective in participants age 65 and older, while Pfizer was 93.7% effective in those age 56 and older. AdventHealth experts agree that both the Pfizer and Moderna COVID-19 vaccines are safe and effective, and we have already started giving vaccinations to health care personnel and older adults. We are distributing both the Pfizer and Moderna vaccines, depending on availability. “It’s an important step in us recovering from COVID-19. It’s a wonderful medical breakthrough and it’s a historical moment that I’m happy to be a part of,” Dr. Simmonds says of the vaccine. There have been reports of certain side effects being linked to the vaccine, but neither company’s vaccines have caused issues that would prevent emergency use authorization from the FDA.