3 leading COVID-19 experts say there isn't clear evidence that healthy, vaccinated people will need booster shots 8 months out

• On Wednesday, US officials recommended a booster shot eight months after a person's second jab.
• Three COVID-19 experts said they weren't sure this was the right strategy to curb the pandemic.
• Ultimately, they said, we need to vaccinate the unvaccinated.

The federal government has recommended COVID-19 booster shots for all.

In a statement on Wednesday, US health officials said all Americans who received an mRNA vaccine from Pfizer or Moderna may get a boost eight months after their second shot. A booster is not yet recommended for people who received a J&J vaccine, which uses different vaccine technology.

"The current protection against severe disease, hospitalization, and death could diminish in the months ahead," the officials said, "especially among those who are at higher risk or were vaccinated during the earlier phases of the vaccination rollout."

Experts in the field weren't particularly surprised at the announcement. The Centers for Disease Control and Prevention, the Food and Drug Administration, and pharmaceutical companies have anticipated that COVID-19 booster doses will eventually be necessary.

But there is some debate about the new plan - including whether it is the right approach to contain the pandemic at this juncture, and who really needs boosters.

John Moore, an immunologist from Weill Cornell Medical College, said he trusted that the Biden administration's recommendation was "science-driven." But like others interviewed for this story, he questioned how much boosting people who are already well protected from disease and death - i.e., fully vaccinated people under 60 who aren't immunocompromised - would affect the pandemic.

"The unvaccinated are the drivers of this pandemic," he said. "If we didn't have 100 million unvaccinated people, we wouldn't be having this kind of conversation because the pandemic would have been squelched in America several months ago."

Why US officials recommend boosters at 8 months

In announcing the new recommendations on Wednesday, the CDC shared a few data sets that influenced its decision.

CDC Director Rochelle Walensky referenced data from Israel and New York, as well as a preprint from the Mayo Clinic, that showed protection from the vaccines waned slightly over time. One study found that the Pfizer and Moderna mRNA vaccines were 75% effective at preventing infection in nursing homes in the spring, but by summer, with Delta spreading, they were 53% effective. Another study found that the two vaccines protected very well against severe COVID-19 and hospitalization for up to six months.

Pfizer's research, meanwhile, suggested that its vaccine was highly protective (91.3% efficacy) against symptomatic COVID-19 for six months after the second dose. On Monday, Pfizer submitted data to the FDA recommending boosters six to 12 months after the second dose. The people in its study received boosters eight to nine months out.

Taken together, these findings suggest vaccine effectiveness does wane over time, especially in the face of the Delta variant. But it's not clear when the optimal time is for a booster shot.

"There's no question that a third dose does increase antibody response," Moore said. "The debate has been whether and when it was necessary to do this."

Walensky said staying ahead of the virus was the biggest motivation driving the eight-month booster recommendation. And vaccines have proved to be our best tool: The US-authorized shots, which were rolled out eight months ago, have protected Americans from symptomatic infection and severe illness and saved hundreds of thousands of lives.

"You don't want to find yourself behind, playing catch up," Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said in a press conference on Wednesday.

Boosters seem to protect vaccinated people from mild illness

Studies have shown that COVID-19 booster doses increase the antibody levels in vaccinated people's blood. Higher antibody levels in general are associated with greater immune protection.

Dr. Robert Atmar, who's leading a booster trial at Baylor College of Medicine, said he suspected boosters could even prevent some cases of long COVID-19 by protecting vaccinated people from mild illness.

"That's always a good thing," Atmar said. But "it may be a little bit of extrapolation to suggest that a booster is warranted," he added.

What is surely warranted right now, Atmar said, is curbing the soaring rate of hospitalizations among the 50% of Americans who remain unvaccinated or partially vaccinated. Boosters might not do much to address that.

"Will it keep more people out of the hospital? Maybe, but I don't know that," he said, adding: "Targeting the unvaccinated would have a greater effect, from a public-health standpoint, if those individuals could be persuaded to accept the vaccine."

Boosters do not solve the real problem: keeping unvaccinated people out of the hospital

Dr. Paul Offit, a pediatrician at the Children's Hospital of Philadelphia and coinventor of the rotavirus vaccine, said the goal of these boosters should be the same as any vaccination: to eliminate "the worst things the virus can do."

Offit, like Moore and Atmar, said that aim would be better achieved by first vaccinating more people who haven't got their first dose, rather than bolstering protection for those who have.

"The real problem in this country is not that we need to boost the vaccinated - it's that we need to vaccinate the unvaccinated," Offit said. "That's the problem. Until we do that, we're going to suffer in this country."

Moore put it even more starkly: "There are 100,000 to 200,000 people walking around America today who will be dead by the end of the year, and mostly self-inflicted, by refusing vaccination," he said. "That's the bigger issue."