Who should get COVID-19 boosters first? CDC committee set to vote Thursday – but only on Pfizer vaccine

A committee of experts spent more than five hours Wednesday reviewing data on the safety and effectiveness of a third shot of the Pfizer-BioNTech COVID-19 vaccine.

The committee, which advises the Centers for Disease Control and Prevention, is scheduled to vote Thursday on precisely who should be eligible for a third shot.

Wednesday night, the Food and Drug Administration authorized a third Pfizer-BioNTech shot six months after the second for people 65-and-older, younger people at high risk for severe disease and those whose jobs put them at extra risk for infection.

The CDC advisory panel, called the Advisory Committee on Immunization Practices, will decide Thursday how to implement that expanded access. CDC director Dr. Rochelle Walensky is expected to quickly sign off on whatever the committee decides, making boosters available to more people within a few days.

The Biden administration had said boosters should become available this week to anyone who completed their initial doses more than eight months ago, but the FDA's panel decided to restrict boosters to a narrower group.

Stay connected: Subscribe to Coronavirus Watch, your daily update on all things COVID-19 in the USA

People who are severely immunocompromised and might not have gotten protection from the first two doses, have been able to get a third dose for the past six weeks or so.

Among the more than 20,000 people who were tracked after receiving a third dose, no major safety concerns popped up, CDC officials said Wednesday. If anything, their side effects were milder than those reported after first and second doses, though their experiences might not be representative.

Only the Pfizer-BioNTech vaccine, now called Comirnaty, would be authorized for the new booster shots, because there is much less data on the long-term effectiveness of the other two authorized shots, from Moderna and Johnson & Johnson.

Parsia Jahanbani prepares a syringe with the Pfizer COVID-19 vaccine in a mobile vaccine clinic operated by Families Together of Orange County on Aug. 26 in Santa Ana, Calif.
Parsia Jahanbani prepares a syringe with the Pfizer COVID-19 vaccine in a mobile vaccine clinic operated by Families Together of Orange County on Aug. 26 in Santa Ana, Calif.

Several ACIP members expressed concern Wednesday that limiting boosters to one company's vaccine would cause confusion and make it more likely for people to switch vaccines – getting a Pfizer-BioNTech booster after two Moderna shots, for instance though there's limited evidence that this is safe.

Among the more than 20,000 Americans who were tracked after receiving a third dose, no major safety concerns popped up, CDC officials said Wednesday. If anything, their side effects were milder than those reported after first and second doses, though their experiences might not be representative.

It's not easy to pronounce. But one thing is certain about FDA-approved Comirnaty: It works

Q&A: When will the Pfizer-BioNTech COVID-19 vaccine be ready for kids?

Data from Israel, which authorized booster shots for its entire population, and from lab studies by the companies, suggests that protection against any infection with COVID-19 begins to fade after about six months. It's not clear whether protection against severe disease will decline after that, but Israeli data suggests it might.

People over 65 saw the biggest decline in protection in the face of the delta variant of the coronavirus that dominates the USA.

Other groups did not show heightened risk for severe disease, according to data presented by the CDC. People with heart disease showed only a slight decline in vaccine protection, and people who are obese saw almost no drop-off. There was no clear difference by race or ethnicity.

Because the immune system's effectiveness declines with age, people older than 65 are likely to get the biggest benefit from a booster dose.

A CDC model of nursing home patients showed clear benefit from a third shot, but they benefited even more when their caregivers were vaccinated and when infection rates were low in the surrounding communities.

No number of boosters will prevent all infections with COVID-19, several committee members said, but Pfizer and BioNTech's data suggest they will improve the immune response, preventing some serious cases and deaths.

Health care workers, who tend to be younger and healthier than the general population, also fared well.

Some areas are so desperate for health care workers because of COVID-19 outbreaks that they can't afford to have people out sick, said committee member Helen Keipp Talbot, a doctor at Vanderbilt University Medical Center in Nashville, Tennessee.

A booster might not save health care workers from severe disease, but it might prevent absenteeism, she said. "The idea would be to maintain necessary and needed staffing levels, because we have such large populations that are unvaccinated (and falling ill)."

The CDC presented updated information showing that COVID-19 vaccination protects pregnant people and their babies against a dangerous infection and is safe for both.

The committee must make its decision on boosters in the face of many questions that have no answers, including whether people who have caught COVID-19 and are vaccinated will benefit from a third shot.

Whatever the committee decides, it isn't likely to be the last word on boosters, several members said. The situation with COVID-19 evolves as data regularly becomes available, said  Dr. Julie Morita, a former committee member and executive vice president of the Robert Wood Johnson Foundation, a health-focused nonprofit group. 

"If the pandemic has done nothing else," she said, "it's made clear that recommendations like this for a vaccination or other preventative measures evolve and change based on the data as it becomes available."

First step: FDA panel recommends Pfizer-BioNTech COVID-19 booster shots only for people 65 and older or at high risk

More on vaccines: Pfizer-BioNTech say low dose of its COVID-19 vaccine is safe and effective for kids 5-11

Contact Elizabeth Weise at eweise@usatoday.com and Karen Weintraub at kweintraub@usatoday.com.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

This article originally appeared on USA TODAY: COVID-19 booster: CDC committee to vote Thursday on Pfizer third dose