White House health officials are cautioning against a rush to panic over the XBB.1.5 omicron subvariant, which has rapidly grown to account for 40 percent of U.S. COVID-19 cases, with officials stating it is not yet known if this version is more dangerous.


White House COVID-19 response coordinator Ashish Jha posted a lengthy Twitter thread on Thursday addressing concerns over the sudden rise of XBB.1.5. He acknowledged that the subvariant going from 4 percent of cases to 40 percent in a matter of weeks was a “stunning increase.”

  • Jha said XBB.1.5 is likely more immune-evasive than other omicron subvariants and could likely be more contagious as well but said it is not yet known if it is more dangerous than previous mutations.
  • “If you had an infection before July or your last vaccine was before bivalent update in September, your protection against an XBB.1.5 infection is probably not that great,” Jha said.

COVID-19 antivirals such as Paxlovid and Molnupiravir, however, should still work in treating infections, Jha said. Paxlovid, a combination of two antiviral medications, functions by blocking an enzyme the SARS-CoV-2 virus needs to replicate.


Food and Drug Administration Commissioner Robert Califf said on Thursday, “It is highly likely that the current bivalent vaccines provide some protection against XBB, especially in the prevention of serious illness and death.”