Your questions, answered "Surprised to read about a fourth dose … Any other studies aside from Israel, referenced too often, that draw the same conclusion?" — Carol in New York Whether and when people should receive a second booster of a coronavirus vaccine has been the subject of widespread speculation almost since the first booster was recommended. There's still disagreement about the answer, even now that Pfizer-BioNTech and Moderna have applied to the Food and Drug Administration for authorization of an additional dose. Pfizer has asked the regulators to authorize another booster only for people ages 65 and older, while Moderna applied for permission to distribute its booster to all adults. Moderna has said it made that broad request to give the Centers for Disease Control and Prevention flexibility in deciding who should receive an additional dose. The FDA is set to meet April 6 to develop a framework for additional booster doses, but it said it would not discuss the companies' specific applications. It's also unclear whether the FDA will approve them. The Biden administration and some health experts have expressed skepticism that additional doses are needed in the short term. You're astute to notice that both Pfizer's and Moderna's applications cited data from Israel's health ministry, which tracked infections and hospitalizations in 1.1 million people ages 60 and older who were eligible for a second booster. That study, not yet peer-reviewed, found that people who received the additional dose had a lower infection rate than those who did not. The rate of severe illness was also significantly lower, although it was unclear how long the extended protection would last. Pfizer's application also referred to a different preprint study from Israel. In that research, which followed health-care workers, a second booster increased virus-fighting antibodies but was not particularly effective at preventing less serious or asymptomatic infections. "That suggests that as a longer-term strategy — and for people who are not at high risk of severe disease — a fourth shot may not be the ideal way to increase immunity," my colleagues Laurie McGinley, Tyler Pager and Carolyn Y. Johnson reported last week. At least some scientists have reached a similar conclusion. Anna Durbin, director of the Center for Immunization Research at Johns Hopkins University, said she's unaware of other studies of second boosters and doesn't believe they're necessary right now. While another dose would increase antibodies temporarily and reduce the risk of infection, she said the current vaccine regimen already protects well against severe disease and death. David Dowdy, an epidemiologist at Johns Hopkins University, also said he could not point to studies of fourth doses in people who are not immunocompromised. "There has been probably an excessive amount of attention paid to data from Israel, coupled with a strong financial incentive to Pfizer/Moderna to recommend a 4th dose," he told The Washington Post in an email. For more on this, check out the opinion article by infectious-disease specialist Monica Gandhi below. | 
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