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.
Hundreds of supporters of South Korea's arrested president, Yoon Suk Yeol, stormed a court building early on Sunday after his detention was extended, smashing windows and breaking inside, an attack the country's acting leader called "unimaginable".
Russian forces unleashed a combined drone and missile strike on the Ukrainian capital Kyiv early on Saturday, killing three people in a central district, officials said.
Donald Trump's incoming US presidential administration plans to intensify immigration enforcement nationwide soon after he takes office on Monday, Reuters reported.
Israel's cabinet approved a deal with Hamas for a ceasefire and release of hostages in the Gaza Strip, Prime Minister Benjamin Netanyahu's office said on Saturday, a day ahead of the agreement's scheduled start.