None of the current evidence on the COVID-19 vaccines shows a need for booster doses in the general population, according to an international group of vaccine experts, including officials from the World Health Organization (WHO) and the Food and Drug Administration (FDA).
"Current evidence does not, therefore, appear to show a need for boosting in the general population, in which efficacy against severe disease remains high," Marion Gruber and Phil Krause, two longtime FDA officials who have been leading the agency's review of COVID-19 vaccine applications, wrote in a paper published Monday. Both Gruber and Krause recently said they are departing the agency later this fall.
Neither FDA official has spoken publicly about their reasons for leaving their longtime posts, but the announcement they were stepping down came as the agency defended the Biden administration's approach to vaccine booster shots.
The paper's publication comes as the administration is pushing for boosters to be widely available to all Americans beginning Sept. 20, despite disagreement from outside scientists and some health agency officials who argue it's premature, and that the data are not strong enough to support such a move.
The Lancet paper's authors noted the effectiveness of all available COVID-19 vaccines against severe disease remains strong, even as protection against symptomatic infection has decreased slightly due to the delta variant.
Federal health officials have argued that booster doses are needed in order to stay ahead of the virus because there's a possibility that the effectiveness against severe disease and hospitalization will wane over time.
But the paper's authors said that's not necessarily true.
Reductions in neutralizing antibody levels "do not necessarily predict reductions in vaccine efficacy over time, and reductions in vaccine efficacy against mild disease do not necessarily predict reductions in the (typically higher) efficacy against severe disease," they wrote.
Experts broadly agree that people with compromised immune systems are likely to benefit from additional vaccine doses; both the FDA and the Centers for Disease Control and Prevention have already signed off on allowing third doses for that part of the population.
But experts are divided on whether boosters are necessary for the general population. An FDA advisory group is meeting Friday to discuss the data to support the wide use of boosters.
The scientists also said there are risks to distributing boosters too soon, including the potential for side effects such as myocarditis, a rare heart inflammation that has been found to be more common after the second dose of mRNA vaccines.
In the paper, the scientists wrote that there is an opportunity right now to study whether boosters against specific variants might be needed before there's a widespread need. There's a possibility a variant emerges that undercuts the vaccine's effectiveness.
But they noted that “the message that boosting might soon be needed, if not justified by robust data and analysis, could adversely affect confidence in vaccines and undermine messaging about the value of primary vaccination.”
The scientists also echoed the views of the WHO in arguing that the current vaccines could "save more lives" if they are used in people who are not yet vaccinated rather than for boosters.
The WHO last week called for a moratorium on boosters in wealthy nations until at least the end of the year.