As FDA OKs Another COVID Booster, Some Experts Question Need

March 29, 2022 // Editor's note: This article has been revised to include the FDA's decision Tuesday to authorize additional boosters from Moderna and Pfizer.

The US Food and Drug Administration (FDA) today authorized Americans over the age of 50 to receive a second COVID-19 booster shot, even though many top infectious disease experts questioned the need before the agency’s decision.

The FDA granted emergency use authorization for both Pfizer and Moderna to offer the second booster — and fourth shot overall — for adults over 50 as well as those over 18 with compromised immune systems.

The Centers for Disease Control and Prevention (CDC) must still sign off before those doses start reaching American arms. That approval could come at any time.

"The general consensus, certainly the CDC's consensus, is that the current vaccines are still really quite effective against Omicron and this new BA.2 variant in keeping people out of the hospital, and preventing the development of severe disease," William Schaffner, MD, an infectious disease specialist at Vanderbilt University Medical Center in Nashville, Tennessee, said prior to the FDA’s announcement Tuesday.

Of the 217.4 million Americans who are "fully vaccinated," ie, received two doses of either Pfizer or Moderna's vaccines or one dose of the Johnson & Johnson vaccine, only 45% have also received a booster shot, according to the CDC.

"Given that, there's no need at the moment for the general population to get a fourth inoculation," Schaffner told Medscape Medical News. "Our current focus ought to be on making sure that as many people as possible get that [first] booster who are eligible."

Monica Gandhi, MD, an infectious disease specialist at the University of California, San Francisco, agreed that another booster for everyone was unnecessary. The only people who would need a fourth shot (or third, if they had the Janssen vaccine initially) are those over age 65 or 70 years, Gandhi said.

"Older people need those antibodies up high because they're more susceptible to severe breakthroughs," she told Medscape Medical News.

To Boost or Not to Boost

Daniel Kuritzkes, MD, chief of infectious diseases at Brigham & Women's Hospital in Boston, Massachusetts, said the timing of a booster and who should be eligible depends on what the nation is trying to achieve with its vaccination strategy.

"Is the goal to prevent to any symptomatic infection with COVID-19, is the goal to prevent the spread of COVID-19, or is the goal to prevent severe disease that requires hospitalization?" asked Kuritzkes.

The current vaccine — with a booster — has prevented severe disease, he said.

An Israeli study showed, for instance, that a third Pfizer dose was 93% effective against hospitalization, 92% effective against severe illness, and 81% effective against death.

A just-published, randomized controlled study in the New England Journal of Medicine (NEJM) found that a booster of the Pfizer vaccine was 95% effective against COVID-19 infection and that it did not raise any new safety issues.

A small Israeli study, also published in NEJM, of a fourth Pfizer dose given to healthcare workers found that it prevented symptomatic infection and illness, but that it was much less effective than previous doses — maybe 65% effective against symptomatic illness, the authors write.

Giving Americans another booster now — which has been shown to lose some effectiveness after about 4 months — means it might not offer protection this fall and winter, when there could be a seasonal surge of the virus, Kuritzkes told Medscape Medical News.

And, even if people receive boosters every few months, they are still likely to get a mild respiratory virus infection, he said.

"I'm pretty convinced that we cannot boost ourselves out of this pandemic," said Kuritzkes. "We need to first of all ensure there's global immunization so that all the people who have not been vaccinated at all get vaccinated. That's far more important than boosting people a fourth time."

Booster Confusion

An April 6 FDA meeting of the agency's Vaccines and Related Biological Products Advisory Committee is still on the docket to discuss additional booster doses.

What the FDA's newest authorizations Tuesday mean for the committee's April 6 meeting is not yet clear. The original agenda said the committee will consider the evidence on safety and effectiveness of the additional vaccine doses and discuss how to set up a process — similar to that used for the influenza vaccine — to be able to determine the makeup of COVID vaccines as new variants emerge. That could lay the groundwork for an annual COVID shot, if needed.

The FDA advisers will not make recommendations nor vote on whether — and which — Americans should get a COVID booster. That is the job of the CDC's Advisory Committee on Immunization Practices (ACIP).

The last time a booster was considered, CDC Director Rochelle Walensky, MD, overrode the ACIP and recommended that all Americans — not just older individuals — get an additional COVID shot.

That past action worries Gandhi, who called it confusing, and said it may have contributed to the fact that less than half of Americans have since chosen to get a booster.

Schaffner predicted the FDA would authorize emergency use for fourth doses of the Pfizer and Moderna vaccines, but he doesn't think the CDC committee will recommend routine use. As we saw before, however, the CDC director does not have to follow the committee's advice.

The members of ACIP "might be more conservative or narrower in scope in terms of recommending who needs to be boosted and when boosting is appropriate," Kuritzkes said.

Gandhi said she's concerned that the FDA's deliberations could be swayed by Moderna and Pfizer's influence and that "pharmaceutical companies are going to have more of a say than they should in the scientific process."

There are similar worries for Schaffner. He said he's "a bit grumpy" that the vaccine makers have been using press releases to argue for boosters.

"Press releases are no way to make vaccine recommendations," Schaffner said, adding that he "would advise [vaccine makers] to sit down and be quiet and let the FDA and CDC advisory committee do their thing."

Moderna Chief Medical Officer Paul Burton, MD, however, told WebMD last week that the signs point to why a fourth shot may be needed.

"We see waning of effectiveness, antibody levels come down, and certainly effectiveness against Omicron comes down in 3 to 6 months," Burton said. "The natural history, from what we're seeing around the world, is that BA.2 is definitely here, it's highly transmissible, and I think we are going to get an additional wave of BA.2 here in the United States."

Another wave is coming, he said, and "I think there will be waning of effectiveness. We need to be prepared for that, so that's why we need the fourth dose."

Supply Issues?

Meanwhile, the United Kingdom has begun offering boosters to its over age 75 years population, and Sweden's health authority has recommended a fourth shot to people over age 80 years.

That puts pressure on the US — at least on its politicians and policymakers — to, in a sense, keep up, said the infectious disease specialists.

Indeed, the White House has been keeping fourth shots in the news, warning that it is running out of money to ensure that all Americans would have access to one, if recommended.

On March 23, outgoing White House COVID-19 Response Coordinator Jeff Zients said that the federal government had enough vaccine for the immunocompromised to get a fourth dose "and, if authorized in the coming weeks, enough supply for fourth doses for our most vulnerable, including seniors."

But he warned that without congressional approval of a COVID-19 funding package, "We can't procure the necessary vaccine supply to support fourth shots for all Americans."

Zients also noted that other countries, including Japan, Vietnam, and the Philippines had already secured future booster doses and added, "We should be securing additional supply right now."

Schaffner said that while it would be nice to "have a booster on the shelf," the US needs to put more effort into creating a globally-coordinated process for ensuring that vaccines match circulating strains and that they are manufactured on a timely basis.

He said he and others "have been reminding the public that the COVID pandemic may indeed be diminishing and moving into the endemic, but that doesn't mean COVID is over or finished or disappeared."

Schaffner said that it may be that "perhaps we'd need a periodic reminder to our immune system to remain protected. In other words, we might have to get boosted perhaps annually like we do with influenza."

Alicia Ault is a Lutherville, Maryland-based freelance journalist whose work has appeared in publications including JAMA, Smithsonian.com, The New York Times, and The Washington Post. You can find her on Twitter @aliciaault.

Kuritzkes disclosed consulting or speaking fees from GlaxoSmithKline, Janssen, Merck, Moderna, and Pfizer. Gandhi has disclosed no relevant financial relationships.

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