He added, though, that people who are vaccinated, and especially those who have their booster shots, will be relatively well protected, at least against severe disease, saying his most worried about the unvaccinated.
He noted that even before omicron is widespread in the U.S., the delta variant is already causing about 120,000 cases and about 1,000 deaths per day, making added pressure from omicron even worse.
During an event organized by the United States Chamber of Commerce, the specialist said that the convergence of both versions of the virus with the flu “things could get really bad, especially for the unvaccinated.”
Omicron is the most transmissible variant of the virus yet, with a doubling time of about three days, Dr. Fauci said. While there is some early information that it could cause less severe illness, that is not assured, he added.