FDA authorizes boosters of the Pfizer-BioNTech coronavirus vaccine for older adults and others at high risk from COVID-19

• The FDA authorized boosters of the Pfizer-BioNTech coronavirus vaccine for older adults and people at higher risk.
• Booster shots are likely to be available in locations like pharmacies and clinics at no cost.
• The US is still struggling to convince many people to get their first doses of coronavirus vaccines.

The US coronavirus booster-shot campaign has cleared a crucial hurdle.

The Food and Drug Administration on Wednesday authorized booster doses of the Pfizer-BioNTech coronavirus vaccine for older adults and others at high risk from the pandemic. Boosters can be given starting six months after the first two doses of the shot. The agency said that getting a third shot is safe and can help increase protection against the disease.

The FDA decision caps more than a month of messy debate over the US vaccination drive. In mid-August, a group of President Joe Biden's top health officials issued an extraordinary joint statement saying that boosters were coming. The statement prompted controversy because it came before reviews by the FDA and the Centers for Disease Control and Prevention, and before much data on the safety or effectiveness of boosters was available.

The US has already greenlit an extra vaccine dose for people with compromised immune systems, and some countries have embarked on booster-shot campaigns focused on vulnerable individuals.

Under the FDA's emergency-use authorization, four main groups of people are eligible for booster shots:

• People 65 and older;
• People 18 to 64 who are at high risk of a severe case of COVID-19 if they get sick;
• People 18 to 64 who are at higher risk of getting COVID-19 at work, such as healthcare workers and teachers;
• People 18 to 64 who are at higher risk of getting COVID-19 because of where they live, such as those in prisons and other institutions.

Protecting the most vulnerable amid the pandemic

The hope is that booster shots will help protect those most at risk as the pandemic continues to surge, fueled by the rise of the Delta variant. Delta is more contagious, and appears to be able to partially elude the protection offered by vaccines.

Still, the US is struggling to convince much of its population to get coronavirus vaccines at all. Just over 64% of people 12 and older are fully vaccinated, according to the CDC.

"At this moment, it is clear that the unvaccinated are driving transmission in the United States," Dr. Amanda Cohn from the CDC said during an FDA meeting on boosters shots on Friday. Cohn said that masks and social distancing are still crucial, because "vaccination will never be perfect" at preventing every case.

The CDC still needs to weigh in formally on who should be prioritized to receive booster doses. The agency's vaccine advisory committee is set to discuss booster shots on Thursday.

The Biden administration has said that once approved, booster shots will be widely available in locations like pharmacies and clinics. They'll be offered to individuals for free.

Expanding the reach of boosters

The FDA decision is a setback for Pfizer, which had asked the agency to make boosters available to everyone over age 16, six months after their second dose.

It comes after a panel of doctors and other experts advising the FDA voted against the idea of making booster shots available that widely. The panel instead said that boosters should be given to people 65 and older, and to those most at risk of severe cases of COVID-19.

Experts on the panel said there wasn't enough evidence showing the benefits of an extra vaccine dose for younger people. They also expressed concern that there wasn't enough safety data for younger adults, highlighting the risk of myocarditis, or heart inflammation, that has been seen at higher-than-usual levels in teenagers and 20-somethings who have been vaccinated.

"The incremental benefit to the younger population really has not been demonstrated at all," Dr. Michael Kurilla, an infectious disease expert from the National Institutes of Health, said during the meeting.

"I think we need to target the boosters right now specifically to the people who are likely to be at high risk, and it's an older population."

'A good step to protect yourself'

Infectious-disease experts who aren't on the FDA's committee said the group made the right call to limit the initial rollout to more vulnerable people.

"If you fall into the age category, this is a good step to protect yourself," said Gigi Gronvall, an immunologist and senior scholar at the Johns Hopkins Center for Health Security.

The booster rollout shouldn't distract from effort to get more unvaccinated people to get their initial shots, said Bernadette Boden-Albala, director of the University of California, Irvine's public-health program.

"If you're not vaccinated, get vaccinated," Boden-Albala said. "If you are vaccinated, be vigilant. And if you're vaccinated and eligible for the booster, get it."

The FDA still has plenty of work ahead on coronavirus vaccines. The agency is reviewing an application from Moderna to give a third shot of its two-dose vaccine. Johnson & Johnson recently put out data showing that its vaccine is more effective after a second dose, and said it'd provided the information to the FDA.

The agency is also being pressed to make vaccines available to younger kids. Pfizer has said it plans to submit data from a study of kids ages 5 to 11 to FDA in early October, and the agency could reach a decision by the end of that month. The drugmaker then plans to submit data from kids between 6 months and 5 years old in November.

The case for boosters

To make the case for booster shots, Pfizer presented results from at least eight studies showing protection from the vaccine wanes over time and that a booster could help. The company also cited data from Israel that showed big benefits from boosters in older people. That data comes from an observational study and could be skewed by factors that researchers weren't aware of or couldn't account for.

The FDA's own review of the evidence for extra shots avoided taking a firm stance on some of the largest questions surrounding boosters, and noted that Pfizer didn't formally evaluate the efficacy of boosters.

In a statement on Friday, Pfizer said that it believes booster shots are "a critical tool in the ongoing effort to control the spread of this virus."

"We continue to believe in the benefits of a booster dose for a broader population," Kathrin Jansen, Pfizer's head of vaccine research & development, said in the statement.