A second COVID-19 vaccine booster shot may be required because the protection against infection will wane, a top U.S. health official said on Jan. 23.
“We may need to boost again,” Dr. Anthony Fauci, President Joe Biden’s chief medical adviser and the longtime head of the National Institute of Allergy and Infectious Diseases, said on ABC’s “This Week.” “That’s entirely conceivable, but before we make that decision about yet another boost, we want to determine clearly what the durability of protection is of that regular boost, that third shot that we’re talking about.”
All Americans aged 12 years or older are advised to get an additional shot, or a booster, because the vaccines’ effectiveness against both infection and severe disease isn’t as good as time goes on from the primary regimen.
Some 83 million Americans, or 40 percent of people who received a primary vaccination series, have received a booster dose as of Jan. 23, according to federal data.
Emerging data indicate that both an initial booster and a second booster restores some of the lost protection against the illness but that the effect quickly wanes.
Data from the United Kingdom, for instance, shows a booster of Pfizer or Moderna was 65 to 75 percent effective against infection 2 to 4 weeks later, but that the effectiveness dropped to 55 to 75 percent at 5 to 9 weeks, and 40 to 50 percent from 10 or more weeks after the additional jab.
The UK analysis found an initial boost to 92 percent effectiveness against hospitalization that dropped to 82 percent 10 or more weeks later.
Asked about a second booster—a fourth jab of Moderna or Pfizer’s vaccine, or a third dose of Johnson & Johnson’s vaccine—Fauci said officials are unsure “because we don’t know the durability of protection” from the first booster.
“Certainly, you are going to see the antibody levels go down,” Fauci, who last month said it was “premature” to be talking about second boosters, told ABC. “That’s natural, but there’s an element of the immune response, B cell memory and T cell responses, where even though you do see a diminution of antibody levels, it is quite conceivable—and I hope it’s true—that the third shot boost will give a much greater durability of protection. We’re following that very carefully.”
Antibodies are considered a main marker of protection against infection while B and T cells are seen as a prime indicator of protection against severe disease.
“When I say protection, I mean protection against severe disease,” Fauci said. “You are going to see breakthrough infections as we’ve seen now, even in boosted people, but for the very most part they’re mild or even asymptomatic.”