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.
Iran said on Sunday it had received a US response to its latest offer for peace talks, a day after President Donald Trump said he would probably reject the Iranian proposal because "they have not paid a big enough price".
The Israeli military issued an urgent warning on Sunday to residents of 11 towns and villages in southern Lebanon, urging them to evacuate their homes and move at least 1,000 metres (3,300 feet) away to open areas.
Ukrainian drones attacked Russia's Baltic Sea port of Primorsk on Sunday, temporarily setting it on fire, local governor Alexander Drozdenko said on the Telegram messaging app, as Kyiv launched a wave of strikes on targets across the country.
An Israeli court has extended by two days the detention of two activists arrested aboard a Gaza-bound flotilla that was intercepted by Israeli forces in international waters near Greece, their lawyer said on Sunday.
Heavy rains that hit northeastern Brazil over the last 48 hours have killed at least six people and displaced thousands in the states of Pernambuco and Paraiba, the federal government said in a statement on Saturday.