The US Food and Drug Administration on Monday gave full approval to the COVID-19 vaccine made by Pfizer and German partner BioNTech for use in people over the age of 16.
It's the first such approval of a COVID-19 shot.
The vaccine has been authorised for emergency use since December and more than 204 million people in the United States have received it, based on Sunday's data.
But none of the three authorised COVID-19 vaccines had previously received full FDA approval.
Public health officials hope it will convince more unvaccinated Americans that Pfizer's shot is safe and effective.
Vaccine hesitancy among some Americans has hindered the United States response to the novel coronavirus.
"While millions of people have already safely received COVID-19 vaccines, we recognize that for some, the FDA approval of a vaccine may now instill additional confidence to get vaccinated," said Janet Woodcock, the US Food and Drug Administration's acting commissioner.
Roughly 51 per cent of Americans have been fully vaccinated so far, even as a recent surge of infections spurred by the contagious Delta variant ravages parts of the country with low vaccination rates.
US President Donald Trump said on Tuesday he had ruled out putting American troops on the ground in Ukraine, but said the country might provide air support as part of a deal to end Russia's war in the country.
A Ukrainian drone attack late on Tuesday knocked out power to areas of Ukraine's Zaporizhzhia region under Russian control, the Moscow-installed governor said.
Israel is demanding the release of all 50 hostages held in Gaza, Israeli public broadcaster Kan cited the prime minister's office as saying on Tuesday, as talks on a proposed deal envisaging a 60-day truce and release of half the hostages continue.
U.S. President Donald Trump said on Tuesday he hoped Vladimir Putin was going to "be good" and move forward toward ending the war in Ukraine, but conceded it was possible the Russian president doesn't want to make a deal.
Aid worker killings rose nearly a third to almost 400 last year, the most deadly year since records began in 1997, and the conflict in Gaza is continuing to cause high death rates for humanitarian staff in 2025, U.N. and other data showed.