President Joe Biden received his COVID-19 booster shot on Monday, days after federal regulators recommended a third dose of the Pfizer vaccine for Americans aged 65 or older and approved them for others with pre-existing medical conditions and high-risk work environments.

"The most important thing we need to do is get more people vaccinated," Biden said before getting the booster.

Centers for Disease Control and Prevention and the Food and Drug Administration authorized the Pfizer booster, Biden told reporters, "I'll be getting my booster shot.

It's hard to acknowledge I'm over 65, but I'll be getting my booster shot.

Biden emerged as a champion of booster doses this summer, as the U.S.

showing that protection against so-called breakthrough cases was vastly improved by a third dose of the Pfizer shot.

was purchasing another 500 million doses of the Pfizer vaccine — for a total of one billion over the coming year — to donate to less well-off countries.

Regulators are also expecting data about the safety and efficacy of a booster for the single-dose Johnson & Johnson shot soon.

At least 2.66 million Americans have received booster doses of the Pfizer vaccine since mid-August, according to the CDC.

About 100 million Americans have been fully vaccinated against COVID-19 through the Pfizer shot.

On Capitol Hill, Senate Republican Leader Mitch McConnell, 79, a polio survivor, encouraged Americans to get vaccinated and revealed he had also received a booster dose Monday.

As of Monday afternoon, more than 232 million cases of COVID-19 had been reported worldwide, according to Johns Hopkins University.

In Europe, President Emmanuel Macron on Saturday said France would give 120 million COVID-19 vaccine doses to poor countries, doubling an earlier pledge, French news agency AFP reported.

In the Americas, Cuba has begun commercial exports of its homegrown COVID-19 vaccines, sending shipments of the three-dose Abdala vaccine to Vietnam and Venezuela. Cuban scientists have said the vaccines are more than 90 per cent effective against illness, though — like all vaccines — less so against mere infection.

The COVID-19 vaccine by Pfizer-BioNTech will be the only one used in Mexico for at-risk children aged 12 to 17, Mexico's deputy health minister said.