It's been 97 days since Pfizer started submitting data for their full approval application from the federal Food & Drug Administration.
Part of that time for the FDA includes inspecting the vaccine manufacturing facilities and clinical trial sites, even monitoring individual patients and going through data of tens of thousands of patients and, given enough time, to also follow them for safety.
Based on those results, the vaccine was 91% effective in preventing COVID-19 disease.
These numbers are from before the Delta variant surge. Early research shows immunity from the MRNA vaccines goes down after roughly 6-8 months.
The FDA's licensure doesn't cover boosters. FDA must approve that separately. The Biden administration is planning for boosters starting in the fall, but the FDA and CDC still must OK it.
The FDA already is allowing emergency use of a third dose of Pfizer or Moderna shots for people with severely weakened immune systems.
Front line health care workers, who have seen a vast majority of those severely sick unvaccinated, tell Newsy they're hopeful this will help in the pandemic fight.
"This stamp of approval is so good, because it will say, look, we have done what we would have done for every other vaccine," says Neysa Ernst, Nurse Manager at Johns Hopkins Hospital. "For your shingles vaccine, for your pertussis vaccine, for your tetanus shot."
The FDA only expanded Pfizer’s vaccine emergency approval for 12-to-15-year-olds on May 10, so it's too early for that group to be included in the full license.
Also still to be decided is vaccination of children under 12. Both Pfizer and Moderna are studying young children, and those findings are expected in the fall.
FDA says it will continue to study the Pfizer vaccine even after approval, including safety studies for pregnancy.
The hope here is that groups that have been hesitant will get vaccinated now. For example, even though the CDC recommends it, right now only about 1 in every 4 pregnant people have gotten a COVID vaccine.