Fauci stressed that he was hypothesizing, based on how the vaccines have held up against other SARS-CoV-2 variants. Studies will need to be done, he insisted. And manufacturers are working on and will test versions of their vaccines based on the mutation-studded Omicron spike protein. That’s prudent, he said.

“The companies are going to be making variant specific boosters,” Fauci told STAT. But “what I think is something that we need to keep our eye on [is] it could be that things turn out better than we expected.”…

“I’m not so sure that we’re going to have to get a variant-specific boost vaccine to get an adequate protection from Omicron,” he said. “Because if you look at protection against variants, it appears to relate to the level of immunity and the breadth of the immunity that any given vaccine can instill on you.”

“We’ve seen also when you boost yet again with the ancestral strain,” — vaccines that target the Wuhan virus — “not with a variant-specific strain, you get a rather dramatic multi-, multi-fold increase [in antibodies] … what I would call a projection or a prediction of protection,” Fauci said.