This is considered the gold standard for medications and vaccines.
FDA officials say they poured over hundreds of pages of data, looking at clinical trials and real-world experience. Officials say Pfizer's vaccine meets all the criteria for approval for ages 16 and older.
SEE ALSO: FDA gives full approval to Pfizer's COVID-19 vaccine
"I think this helps solidify that these vaccines are extremely safe and very effective," said Dr. Eric Sachinwalla, an infectious disease specialist with Einstein Medical Center.
Dr. Sachinwalla said the Covid-19 vaccines are now some of the most studied medications.
Pfizer CEO Albert Bourla called the FDA's action "an important milestone that I think will unlock some of the more skeptical minds."
Pfizer said the U.S. is the first country to grant full approval of its vaccine, in a process that required a 360,000-page application and rigorous inspections. Never before has the FDA has so much evidence to judge a shot's safety.
The formula, jointly developed with Germany's BioNTech, will be marketed under the brand name Comirnaty.
The approval will likely spark more companies and colleges to require vaccination.
In New Jersey, Governor Phil Murphy issued a COVID-19 vaccine mandate for New Jersey school workers and state employees on Monday.
Dr. Sachinwalla said many vaccines that prevent communicable diseases are already mandated. He also said this one could bring us closer to ending the pandemic.
"The goal has to be to get as many people vaccinated as possible to reach some form of herd immunity," said Dr. Sachinwalla.
A poll by Kaiser Family Foundation in June also shows 31% of people still unvaccinated said they were more likely to get the shots if the FDA granted approval.
Dr. Drew Weissman at Penn Medicine hopes so. He laid the groundwork for the mRNA vaccines almost two decades ago.
"The efficacy is still fantastic and the adverse events are minimal," he said. "There have really been no serious adverse events, nothing unexpected. People should feel very comfortable."
And as for medical exemptions, Dr. Sachinwalla says there are few.
"People who have had a reaction or some form of anaphylactic reaction to either the first dose of the vaccine or a component of the vaccine," he said.
And, like many vaccines, the approval also comes with a warning label saying there is a slight risk for myocarditis or heart inflammation especially in men under 40
Most cases fully resolve and the benefits of the vaccine still greatly outweigh the risks.
The Associated Press contributed to this report.