Omicron BQ Covid variants, which threaten people with compromised immune systems, are now dominant in U.S.

The omicron BQ coronavirus subvariants have risen to dominance in the U.S. as people gather and travel for the Thanksgiving holiday, putting people with compromised immune systems at increased risk.

BQ.1 and BQ.1.1 are causing 57% of new infections in the U.S., according to data published by the Centers for Disease Control and Prevention on Friday. The omicron BA.5 subvariant, once dominant, now makes up only a fifth of new Covid cases.

The BQ subvariants are more immune evasive and likely resistant to key antibody medications, such as Evusheld and bebtelovimab, used by people with compromised immune systems, according to the National Institutes of Health. This includes organ transplant and cancer chemotherapy patients.

There are currently no replacements for these drugs. President Joe Biden, in an October speech, told people with compromised immune systems that they should consult with their physicians and take extra precautions this winter.

“New variants may make some existing protections ineffective for the immunocompromised. Sadly, this means you may be at a special risk this winter,” Biden said.

The XBB subvariant is also circulating at a low level right now, causing about 3% of new infections. Chief White House medical advisor Dr. Anthony Fauci, in a briefing Tuesday, said XBB is even more immune evasive than the BQ subvariants.

Fauci, director of the National Institute of Allergy and Infectious Diseases, said the new boosters, which were designed against omicron BA.5, probably aren’t as effective against infection and mild illness from XBB. But the shots should protect against severe disease, he said. Singapore saw a spike in cases from XBB, but there wasn’t a major surge in hospitalizations, he added.

Moderna and Pfizer said last week that their boosters induce an immune response against BQ.1.1, which is a descendent of the BA.5 subvariant.

Fauci, in the press briefing, said public health officials believe there is enough immunity from vaccination, boosting and infection to prevent a repeat of the unprecedented Covid surge that occurred last winter when omicron first arrived.