WASHINGTON — Advisers to the US Food and Drug Administration voted on Friday to recommend COVID-19 vaccine booster shots for Americans 65 and older and those at high risk of severe illness, after overwhelmingly rejecting a call for broader approval, according to Reuters.

The panel also recommended that the FDA include healthcare workers and others at high risk of occupational exposure to the virus that causes COVID-19, such as teachers.

Despite the narrowed scope of the proposed authorization, the panel's recommendation would cover most Americans who got their shots in the earliest stages of the US vaccination campaign.

"Today was an important step forward in providing better protection to Americans from COVID-19," White House spokesperson Kevin Munoz said. "We stand ready to provide booster shots to eligible Americans once the process concludes at the end of next week," he said.

The FDA is expected to make its decision on the third round of shots soon. It is not bound by the panel's recommendation but will take it into consideration.

The panel has recommended boosters of Pfizer's Covid-19 vaccine for people 65 and over, and those at high risk. But it voted against recommending a shot for everyone aged 16 and over.

The outcome is a blow for President Joe Biden, who said widespread jabs would be available by next week if approved. The FDA's scientific advisory committee voted 16 to 3 against the boosters for those aged 16 and over.

Many of the panel's independent experts — including infectious disease specialists — said scientific data suggested a widespread roll-out of vaccines was not warranted.

Ahead of a meeting on Friday, some scientists said they believed that boosters were unlikely to have a significant impact on the course of the pandemic.

Dr. Monica Gandhi, an infectious diseases physician and professor at the University of California San Francisco, said she was not convinced by the immunology research.

"Antibodies do come down over time, but [the human body] has the blueprint to make more," she told the BBC.

These blueprints come in the form of "memory B" cells that form part of the adaptive immune system. "There's been paper after paper that shows good circulating memory B cells after the second dose," Dr. Gandhi said.

Some have also said that additional vaccine doses would be more useful if distributed to parts of the world where many people have yet to receive their first or second jabs.

"If you take away the moral and ethical questions, there's still the public health question of where the next variant is going to come from," she said. "It's likely to come from places with low vaccination rates."

Advocates of the booster point to data that shows the Pfizer vaccine's effectiveness against COVID-19 falls from 96% to 84% after four months. Pfizer says that a third shot brings its effectiveness back up to 95% — including against the fast spreading Delta variant.

Dr. Priscilla Hanudel, a Los Angeles-based emergency doctor, said immunocompromised people "definitely" need to get a booster.

She said she also believes that the general public would benefit from boosters, even if they remain well protected from severe illness after the second shot.

"Just like with any vaccine, all immunity will wane over time, and in the next month we're going to be seeing that," Dr Hanudel said. "If not enough people are vaccinated and the pandemic continues, then everyone will need their immunity boost eventually, as with other vaccines," she said.

In the UK, the government has announced that it will offer boosters to everyone over 50 and to other vulnerable people as it heads towards the winter months.

Germany, France and the Czech Republic have announced similar plans for older or vulnerable people. In Israel, boosters are already being offered to people as young as 12.

The World Health Organization has called on wealthier nations to hold off on providing booster shots until vaccination rates go up in lesser developed countries.

"There are countries with less than 2% vaccination coverage, most of them in Africa, who are not even getting their first and second dose," WHO Director-General Tedros Adhanom Ghebreyesus said earlier this week. "And starting with boosters, especially giving it to healthy populations, is really not right." — Agencies