Research shows that the protection from the first two doses of either the Pfizer or the Moderna vaccine waned substantially against the omicron variant, though a booster shot restored much of that protection. But the CEOs of Pfizer and Moderna have argued in recent weeks that a fourth dose may now be needed to protect against serious illness from omicron.
To be sure, the evidence that drugmakers have shared isn’t all that compelling to some scientists, said Dr. Jesse Goodman of Georgetown University, a former FDA vaccine chief.
One of the studies, published in February by the Centers for Disease Control and Prevention, found that the effectiveness of Pfizer’s and Moderna’s vaccines against hospitalization decreased from 91 percent two months after the initial booster shot to 78 percent after four months. Another study, according to Pfizer in a news release, found rates of severe illness were four times lower among individuals who received a second booster dose of the vaccine, compared to those who received only one booster shot.
Goodman said protection against severe illness from a third dose appears to be holding up. He’s “not convinced” that the boost in antibody levels from a fourth dose would translate into stronger protection.
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