U.S. health regulators on Monday fully approved Moderna’s COVID-19 vaccine, which has been administered to tens of millions of Americans since emergency authorization was granted more than a year ago.

The FDA’s action means the agency has completed a rigorous, time-consuming review of Moderna’s vaccine, like dozens of other time-honored vaccines.

Since the FDA approved the vaccine in December 2020, more than 200 million doses have been administered in the U.S., a decision supported by real-world evidence. Last August, the FDA fully approved Pfizer’s vaccine.

Public health advocates initially hoped that the regulatory distinction would increase public confidence in injections. But there has been no significant uptick in vaccinations following a push for approval by Pfizer President Joe Biden and other federal officials. Still, regulators said on Monday they hoped the additional recognition would encourage more people to get vaccinated.

More than 211 million Americans, or 63 percent of the population, are fully vaccinated. About 86 million people received booster doses. Vaccinations peaked last spring at more than 3 million a day and now average less than 750,000 a day. Vaccination surged after news of the omicron variant in December, but has since slowed again.

The FDA reviewed several months of additional follow-up data submitted by Moderna to confirm the vaccine’s effectiveness against COVID-19. The FDA also analyzes and pays close attention to serious side effects that have proven to be very rare. The vaccine includes a warning about a rare form of heart inflammation that occurs mostly in young men after a second dose. Most cases are mild and get better quickly.

Not a Modern Healthcare subscriber? Register today.

In addition, the FDA reviewed the company’s manufacturing process and facilities.

“The public can rest assured that the approval of this vaccine met the FDA’s rigorous scientific standards,” Dr. Peter Marks, the FDA’s top vaccine regulator, said in a statement.

After being fully approved, Moderna will now market the vaccine under the Spikevax brand. This is the Cambridge, Massachusetts-based company’s first FDA-approved product.

In the U.S., Moderna is used only by adults for initial vaccinations and half-dose boosters. The company said last fall that the FDA delayed a decision on whether to clear the injection for children aged 12 to 17 while examining the risk of inflammation in the heart.

Johnson & Johnson has yet to apply for full approval of its COVID-19 vaccine.