FDA Approves First COVID-19 Vaccine

"If we look at a more conservative estimate — if we can get 10 percent more of the eligible population vaccinated against COVID — that's going to make a huge difference with regards to community transmission,” Limaye says. Nearly 90 percent of U.S. counties are experiencing high levels of virus transmission, according to the CDC.

The approval process for Pfizer's vaccine, which will now be marketed as Comirnaty, was based on safety and effectiveness data from a large clinical trial population. More than half of the trial participants were monitored for safety for at least four months after the second dose; about 12,000 recipients have been followed for at least six months.

Overall, the vaccine was found to be 91 percent effective in preventing COVID-19 disease in the population studied, and the most commonly reported side effects were pain, redness and swelling at the injection site, fatigue, headache, muscle or joint pain, chills and fever. Safety monitoring will continue, the FDA says, including for risk of myocarditis and pericarditis following vaccine administration.

In addition to evaluating “hundreds of thousands of pages” of data, FDA officials also “performed a detailed assessment of the manufacturing processes, including inspections of the manufacturing facilities,” as part of the approval process, Peter Marks, M.D., director of the FDA's Center for Biologics Evaluation and Research, said in a statement.

"The public and medical community can be confident that although we approved this vaccine expeditiously, it was fully in keeping with our existing high standards for vaccines in the U.S.,” he added.

Pfizer's approval could also spur vaccine mandates at more businesses and organizations throughout the U.S., which could drive up vaccinations. So far about 51 percent of the total U.S. population is fully vaccinated.

Vaccines are still ‘highly effective’ in fight against virus

Reports of breakthrough infections are on the rise, but Limaye says that should not dissuade people from getting vaccinated. Health officials maintain that all three vaccines available to the public — from Pfizer-BioNTech, Moderna and Johnson & Johnson — are still “highly effective” at preventing severe illness and death from the coronavirus, including from the delta variant.

"What we want to do is we want to prevent deaths from happening,” Limaye says. “So we need to keep our eyes focused on that number. And the fact that all of our products that we have in the U.S. that are [authorized] are still holding up quite well is really quite something.”

Nearly all of COVID-19-related hospitalizations and deaths are occurring in unvaccinated people, experts stress. Less than 1 percent of fully vaccinated people have had a breakthrough infection that has resulted in hospitalization or death, CDC data shows.

Next up: Moderna applied for FDA approval for its two-dose vaccine in June and is awaiting the agency's decision; Johnson & Johnson is expected to submit its application for the company's one-dose shot soon. These two vaccines still remain available under emergency use authorization, and all three vaccines continue to be free to the public. Federal officials are also expected to green-light booster shots for vaccinated Americans next month.

Rachel Nania writes about health care and health policy for AARP. Previously she was a reporter and editor for WTOP Radio in Washington, D.C. A recipient of a Gracie Award and a regional Edward R. Murrow Award, she also participated in a dementia fellowship with the National Press Foundation.