COVID-19 booster shots may be coming for at least some Americans but already the Biden administration is being forced to scale back expectations — illustrating just how much important science still has to be worked out.
The initial plan was to offer Pfizer or Moderna boosters starting Sept. 20, contingent on authorization from U.S. regulators. But now administration officials acknowledge Moderna boosters probably won’t be ready by then — the Food and Drug Administration needs more evidence to judge them. Adding to the complexity, Moderna wants its booster to be half the dose of the original shots.
When to jump to boosters “becomes a judgment,” said Dr. Jesse Goodman of Georgetown University, a former FDA vaccine chief. “And is that urgent or do we have time for the data to come in?” But vaccines’ main purpose is to prevent severe disease. “It’s a very high bar to really go and say we can completely block infection,” Ellebedy noted.
But antibodies are only one defense. If an infection sneaks past, white blood cells called T cells help prevent serious illness by killing virus-infected cells. Another type called memory B cells jump into action to make lots of new antibodies. The timing matters because the immune system gradually builds layers of protection over months. Give a booster too soon, before the immune response matures, and people can miss out on the optimal benefit, said Dr. Cameron Wolfe, an infectious disease specialist at Duke University.
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