FDA Authorizes Pfizer Booster for Seniors and High Risk Groups. What's Next?

The Food and Drug Administration (FDA) authorized a third dose of Pfizer’s COVID-19 vaccine for seniors and high risk groups who received their second shot at least six months earlier.

Following the FDA authorization, a Centers for Disease Control and Prevention (CDC) advisory panel unanimously voted in favor of the booster for people aged over 65 and for residents of long-term care facilities. The panel also recommended the booster for those aged 18 and above who have underlying medical conditions.

Pfizer Senior Vice President William Gruber, MD, presented data at Wednesday’s meeting, showing that a third shot of its mRNA vaccine provided a substantial boost in protection against multiple variants. He also pointed to data from the United States and Israel showing that Pfizer’s vaccine efficacy wanes between six and eight months after the second dose.

Gruber said the company is also in the process of developing a model for variant-specific vaccines that may not need to undergo lengthy clinical trials.

The CDC panel noted that the rare risk of heart inflammation, or myocarditis, has been added to the mRNA vaccine fact sheets. The predicted risk of myocarditis associated with the third shot appears to be very low, the panelists said.

Why Are Boosters Only Recommended for Certain Groups?

A booster shot’s potential in improving immunity, combined with the rare side effects observed, could warrant recommending the shot for certain populations, panelists said. But insufficient data on the booster's efficacy in people younger than 18, and on the Moderna and Johnson & Johnson vaccines, could be reasons to withhold or delay the decision.

Anthony Harris, MD, MPH, associate medical director for WorkCare, tells Verywell that the lack of data on the effectiveness of boosters highlights the importance of being selective about eligibility. 

He adds that doctors should evaluate people’s individual antibody levels via a blood test when determining whether they should get a booster. Those with waning antibodies will be more in need of a boosters.

“It’s going to help prevent hopefully a significant number of people from having to undergo a booster who may not need it,” Harris says.

While the adverse side effects associated with a booster may be rare and mild, Harris said that physicians should always avoid administering an unnecessary treatment.

“The classic oath that we take as providers as a physician is to ‘first do no harm,’” he says. “If the booster is not needed because you have an individual with longstanding immunity, then there's no advantage to it.”

What About People Who Received a Moderna or Johnson & Johnson Vaccine?

The panelists said more data is needed before authorizing Moderna or Johnson & Johnson boosters. Since the Moderna vaccine is also made with mRNA technology, the effect of its booster could be more comparable to that of Pfizer's, Harris explains. For Johnson & Johnson, however, there is limited data on the effectiveness of a booster.

Johnson & Johnson released interim data in August saying that its booster shot could increase immunity nine-fold. Moderna has also said that its half-dose booster could boost immune responses in vaccinated people.

Harris stresses the need for more studies and data on the single-dose Johnson & Johnson vaccine because it offers less protection. The Johnson & Johnson vaccine was 66.3% effective against COVID-19 infection in clinical trials, though more recent data shows it's 79% effective. Not every Johnson & Johnson recipient needs a booster currently, unless they have underlying conditions that make them more vulnerable to the virus, he adds.

Some CDC panelists also noted that authorizing a Pfizer booster while leaving out Moderna and Johnson & Johnson could lead to equity issues. The safety and effectiveness of mixing and matching vaccines is also understudied, prompting panelists to refrain from making a booster recommendation for those who previously received doses of a vaccine other than Pfizer's.

Panelist Sarah Long, MD asked the group to consider the pros and cons of waiting another month or two to authorize the booster, to give the other vaccine companies some time to catch up.

“I don't want to jeopardize anyone,” Long said. “At the same time, it will be very very difficult to have a little less than half of the population who are eligible to be able to receive [a booster].”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.