A large wave of Covid infections is projected to hit the U.S. this fall. Booster shots targeting omicron's BA.5 subvariant are the country's "best guess" at a solution, according to Dr. Anthony Fauci.
"As we get into the fall, you'd want to boost with a BA.5 [vaccine] — so that if you get BA.5 or something closely related to that, you will enhance the immunity against that particular variant," Fauci, President Biden's chief medical adviser, said on Hill.TV's "Rising" on Monday.
The seven-day average of new daily cases in the U.S. is nearly 125,000 as of Monday, according to the CDC — and BA.5 currently accounts for nearly 82% of confirmed cases. It appears to be Covid's most transmissible strain to date, driving both new infections — likely including the president — and reinfections in people who previously recovered from Covid.
BA.5 could spread even more aggressively in the fall, as vaccine immunity wanes and people spend more time indoors — and booster shots specifically formulated to fight the subvariant may serve as an added layer of protection.
Last month, the U.S. Food and Drug Administration recommended that drugmakers like Pfizer and Moderna develop bivalent booster shots by the fall. Those are shots designed to bring greater immunity because they target two strains: the original Covid strain and BA.5.
"That's a pretty good estimation of what we will be seeing in the fall," Fauci said.
Now, at the FDA's request, drugmakers are scrambling to develop those boosters. Both Pfizer and Moderna have indicated that their updated shots could be available in October, but federal health officials reportedly told the Washington Post last week that they're hoping for early- to mid-September instead.
If the drugmakers can deliver on that timeline, the FDA will likely skip the authorization of a second booster shot based on currently available Covid vaccines for most U.S. adults, officials reportedly told the Post.
The success of BA.5-specific boosters in the fall is at least partially dependent on the subvariant remaining dominant in the coming months. On Monday, Fauci noted the difficulty of predicting how Covid will mutate in the future — but said that, at least for now, the U.S. is in "BA.5 mode."
"There's always the possibility that you're going to have the evolution of another variant," Fauci said. "And hopefully, if that occurs, it will vary off from the BA.5 only slightly — in the sense of being a sub-sub-lineage of it, and not something entirely different. That's the situation you always face when you're dealing with a moving target."