Dr. Stanley Plotkin is a towering figure in the world of vaccines. The Philadelphia physician invented the rubella vaccine in 1964 and wrote the standard textbook on vaccinology, “Plotkin’s Vaccines.”
He supports President Biden’s proposal last month to offer all recipients of the Pfizer-BioNTech and Moderna COVID-19 vaccines a third shot starting Sept. 20 to boost immunity.
His protege at Children’s Hospital of Philadelphia, Dr. Paul Offit, helped edit Plotkin’s 1,720-page tome, coinvented the vaccine to help prevent rotavirus infections (with Plotkin), and calls his mentor a “God-like figure.”
But Offit says it would be premature to broadly roll out a third dose of either messenger RNA vaccine.
As an advisory panel to the US Food and Drug Administration prepares to meet Friday to consider Pfizer’s request for a third dose, the disagreement illustrates the lack of consensus within the scientific community over the role and timing of booster shots. Some scientists are drawing different conclusions from the latest surge of COVID-19 infections and studies about declining antibody levels in the vaccinated.
Given that a number of medical experts have expressed reservations about boosters, it’s uncertain whether the FDA advisory panel will recommend endorsing the plan announced by the Biden administration on Aug. 18. There are even divisions within the administration, as some federal health officials have since urged the White House to scale its plan back.
That, said Plotkin, would be a mistake.
“I don’t say this to praise myself, but I could have predicted one would need a third dose in order to fully evoke the immune system to raise antibodies to COVID,” said Plotkin, an 89-year-old professor emeritus of virology at the University of Pennsylvania. “The evidence is clear that a third dose raises antibodies and broadens antibodies.”
Plotkin, who has served as a paid consultant to Moderna on its two-dose vaccine, objects to labeling third doses of mRNA vaccines as booster shots. He said a third shot — to be administered several months after the second — is necessary to fully arm the immune system, and after that, recipients might not need additional doses. (Plotkin also has advised Johnson & Johnson on its one-dose vaccine, which uses different technology.)
Offit, 70, who sits on the FDA advisory committee that will vote on whether to recommend third doses, agrees that the Pfizer and Moderna vaccines will probably turn out to be three-shot regimens, as is true of some other vaccines, including one for hepatitis B. But a third dose of the two mRNA coronavirus vaccines is unnecessary now for most people, he said.
Although breakthrough infections in fully vaccinated people have caused alarm, Offit said, few of those cases have resulted in serious illnesses requiring hospitalization. Most cases have been asymptomatic or mild. This proves that the Pfizer and Moderna vaccines continue to work as planned, he said, providing remarkably good protection despite the spread of the highly infectious Delta variant.
Offit said federal health officials should concentrate on vaccinating the millions of eligible Americans who have yet to get shots. (After Offit’s interview with the Globe, the Biden administration did that Thursday by mandating shots for 100 million Americans, including some private sector employees and the vast majority of federal workers.) Boosting the immunity of people who already received two shots can wait at least a year, Offit said.
“I agree with Dr. Plotkin that when the dust settles, this will be a three-dose vaccine and that a third dose will broaden and extend the immune response,” said Offit, who began a fellowship in pediatric infectious diseases at Children’s Hospital under Plotkin in 1980 and now directs the Vaccine Education Center there. “The question is: Why do this now? Instead of taking on this massive booster program for the 170 million people who have already gotten vaccinated, we should take on a massive program for the 60 or 70 million who haven’t gotten vaccinated yet.”
Plotkin said the efforts aren’t mutually exclusive.
“Although I respect Paul very much, I beg to disagree,” he said.
On Aug. 18, Biden said that if the FDA approved it, the government would start offering boosters the week of Sept. 20 to adults who had received their second shot of the Pfizer or Moderna vaccine eight months earlier. That would include many health care workers and nursing home residents, as well as some people older than 65, who were generally among the first to receive vaccines. Administration officials said recipients of the single-dose Johnson & Johnson vaccine would probably be offered an additional shot soon, too. The FDA already has already authorized additional shots for certain people with weakened immune systems, including recipients of organ transplants and some cancer patients.
In recent days, however, federal health officials have recommended the White House tap the brakes on a broader rollout of third shots to the general public.
Among the reasons for a postponement is the need for regulators to have more time to decide the proper dosage for a possible third Moderna shot. Dr. Anthony Fauci, the nation’s leading infectious disease expert, said on CBS’s “Face the Nation” recently that federal health officials were hoping to roll out third shots of the Pfizer and Moderna vaccines simultaneously, but it could be a “few weeks delay” for a Moderna booster.
The FDA also has sought raw data from Israel, which is already giving booster shots to anyone 12 and older. Israeli officials have said their data indicate that the potency of Pfizer’s vaccine to protect against severe disease and hospitalization wanes over time, but that a third shot sharply bolsters its effectiveness.
Sharon Alroy-Preis, head of public health at Israel’s Health Ministry, said the FDA has asked her agency to brief the advisory panel when it meets, according to a recent Reuters story.
Offit, who as a member of the FDA advisory committee voted to recommend the agency clear all three vaccines for emergency use, wants to review briefing materials from regulators before deciding on the booster question. But he’s skeptical a third shot is necessary now. He also wants to see the wording of the question that the FDA puts to the advisory panel.
Offit said it’s possible the agency will only ask whether a third Pfizer shot is safe and boosts the immune response of recipients; the answer to both, in his mind, would probably be yes. The issue of whether the federal government should actually deploy boosters and who should get them, he said, may end up in the hands of a separate panel of experts that advises the US Centers for Disease Control and Prevention.
Dr. Eric Rubin, an immunologist at the Harvard T.H. Chan School of Public Health and member of the same FDA advisory committee as Offit, said he is keeping an open mind. But he, too, says a lot depends on how the FDA frames the question.
“If they asked if the risk/benefit analysis is favorable for people over 95 years old to get a third dose, that would be very different from 12-year-olds,” Rubin, editor in chief of the New England Journal of Medicine, said in an e-mail.
But another vaccine expert was skeptical that a third dose was needed soon.
Dr. Deepta Bhattacharya, a professor of immunobiology at the University of Arizona College of Medicine who is not on the FDA panel, said it’s normal for antibody levels to fall over the course of several months. Vaccination triggers a “blood-thirsty competition” among antibodies, he explained, and only the best ones survive ― “the antibodies that stick most tightly to the virus.”
“The actual evidence that there’s substantial waning of immunity” in recipients of the coronavirus vaccines in important measures “like hospitalization is very weak,” said Bhattacharya.
He might support offering booster shots soon for people over the age of 60 or 70 because their immune responses may decline faster than those of younger people. “Below the age of 60 or for everyone ― I don’t see a whole lot of justification for that,” he said.
Jonathan Saltzman can be reached at firstname.lastname@example.org.