A Food and Drug Administration (FDA) advisory panel voted 18-0 to authorize a Pfizer booster shot for Americans 65 years and older and those at risk of severe COVID-19 infection.

The panel also voted to authorize a booster shot for those who are at risk of severe COVID-19 due to their job, including health care workers, teachers, and essential infrastructure workers.

In a blow to President Joe Biden's vaccine plan, the panel previously voted not to approve the booster shots for all Americans.

Biden had previously said that booster shots would be available for Americans by Sept. 20.

In data released by the FDA on Wednesday, Pfizer argued that vaccine booster shots were not only safe and effective but would be necessary for all Americans over 16, because real-world studies show the effectiveness of the first two doses wanes over time.

The data also showed that a third vaccine dose restored efficacy in preventing COVID-19 to up to 95%.

The Associated Press reports that the panel voiced frustration that Pfizer had provided little data on the safety of the extra doses, and wouldn't dramatically change the arc of the pandemic if all Americans were offered a booster shot.

The Centers for Disease Control will meet next week to review the panel's decision.

BUDAPEST, Hungary (AP) — The head of the World Health Organization has called for a two-month moratorium on administering booster shots of COVID-19 vaccines as a means of reducing global vaccine inequality and preventing the emergence of new coronavirus variants.

WHO Director-General Tedros Adhanom Ghebreyesus told reporters in Hungary’s capital Monday that he was “really disappointed” with the scope of vaccine donations worldwide.

He called on countries offering third vaccine doses to forward what they would use for booster shots to other countries so they can increase their vaccination coverage.

Tedros said that vaccine injustice and vaccine nationalism increase the risk of more contagious variants like the delta variant emerging.

Several countries have started giving the COVID-19 booster shot or plan to administer it in the fall.

The U.S. will begin offering booster shots in September to people who were fully vaccinated eight months prior. President Joe Biden was asked about whether the U.S. should be giving booster shots while other countries struggle to get the vaccine. He said that the U.S. can help other countries and offer booster shots to its people.

"We can take care of America and help the world at the same time," Biden said.

The Biden administration announced in early August that it had donated 110 million COVID-19 vaccines to 65 different countries.