Federal regulators authorized second booster shots of the Pfizer-BioNTech and Moderna coronavirus vaccines on Tuesday for everyone 50 and older. The move came after the Biden administration decided it should seek to bolster waning immunity in older Americans against severe disease in case the virus sweeps the nation again in the coming months.
The Food and Drug Administration said that those who are eligible can get the additional shot at least four months after their first booster. The agency also authorized a second booster for individuals 12 and older with certain immune deficiencies after the same interval.
The decision means that tens of millions of Americans are now eligible for another shot. Federal health officials initially considered limiting second boosters to those at least 60 or 65 years old. But at a news briefing, Dr. Peter Marks, who oversees the F.D.A.’s vaccine division, said a lower age limit made more sense because so many Americans over 50 have underlying medical conditions that put them at risk.
The Centers for Disease Control and Prevention said it would update its vaccine guidance to reflect the F.D.A.’s action. While she did not outright recommend a second booster for everyone now eligible, Dr. Rochelle P Walensky, the C.D.C.’s director, said the option for the added dose “is especially important for those 65 and older and those 50 and older with underlying medical conditions that increase their risk for severe disease.”
Dr. Marks went a bit farther, saying those 50 and older who got their first booster more than four months ago, “should seriously consider getting another.”
The F.D.A. made the decision with very limited data and clearly views it as an interim measure. Federal health officials have said that in the fall, everyone, including those who get a second booster now, may need another shot, perhaps with a vaccine modified to better shield against variants.
“At some point we’re going to have to realize that this is a virus that’s going to be with us and that we have to come to grips with dealing with it on a regular basis,” Dr. Marks said.
Still, the idea that another dose is already necessary, just six months after federal regulators authorized the first round of boosters, could add to public fatigue with Covid vaccines. Dr. Eric Rubin, an infectious diseases expert at the Harvard T.H. Chan School of Public Health, said at this point, “each additional dose is offering marginal value.”
On the other hand, evidence now suggests that the government’s decision last fall to authorize a first booster — the subject of much scientific debate at the time — saved lives during the winter Omicron wave. According to the C.D.C., while that variant surged, those who were boosted were 21 times less likely to die from Covid and seven times less likely to be hospitalized than those who were unvaccinated.
The strongest data in support of a second booster came from a newly released Israeli study that has not yet been peer reviewed. During a 40-day period earlier this year, the researchers studied Covid death rates among more than half a million adults 60 to 100 years old who had received at least one booster.
Among the 234,868 who had only one booster, 232 people died of Covid. Among the 328,597 people who got a second booster, 92 died of Covid. The mortality rate “was significantly lower among those who had received an additional booster,” the researchers said.
Federal officials also studied statistical models that suggested that if the virus surges again in late spring or summer, a second booster could save thousands of lives and avoid tens of thousands of hospitalizations.
The C.D.C. also extended booster coverage to adults who initially got Johnson & Johnson’s vaccine. The agency has already recommended Moderna’s or Pfizer’s vaccine over Johnson & Johnson’s. On Tuesday, the agency said all adults who got an initial dose plus a booster of Johnson & Johnson’s vaccine are eligible for a second booster with one of the mRNA vaccines.
The regulatory moves were complicated because no one knows how long protection from a second booster will last. Pfizer and BioNTech have said that data collected during the Omicron wave showed the potency of an initial booster wanes within three to six months, against both symptomatic infection and severe disease. Data from Israel suggests a second booster restores protection, but the follow-up period is short.
Neither the F.D.A. nor the C.D.C. convened their outside committee of experts to debate the new policy, sparking criticism. Dr. Rubin, a F.D.A. panel member, called that decision reasonable but said it was critical for the agency to make public any data it relied upon for others to scrutinize.
Like other experts, Dr. Rubin said what is really needed now is a vaccine that works better than the existing ones against the new variants. Many studies are now underway to find it, but the earliest results are not expected until later this spring.
“It’s not actually clear yet what the optimal booster should be,” Dr. Marks said.
The F.D.A. panel is scheduled to meet on April 6 to discuss what the nation’s booster strategy should be moving forward.
For the roughly three percent of Americans with immune deficiencies, the decision authorizes what would essentially be a fifth shot for many of them. Those 12 and older can get Pfizer’s shot, while those adults can pick between Pfizer’s and Moderna’s.
Kitty Bennett contributed research.