Omicron subvariants resistant to key antibody treatments are increasing every week in the U.S.

Two omicron subvariants that are resistant to key antibody treatments are on the rise in the U.S., according to data from the Centers for Disease Control and Prevention.

The subvariants BQ.1 and BQ.1.1 now represent 27% of infections in the U.S., a significant jump from the week prior when they made up about 16% of new cases, according to CDC data published Friday.

Omicron BA.5, though still the dominant variant, is diminishing every week. It now represents about 50% of infections in the U.S., down from 60% the week prior, according to the data.

President Joe Biden this week cautioned people with compromised immune systems that they were particularly at risk this winter because antibody treatments are not effective against emerging subvariants.

BQ.1 and BQ.1.1 are likely resistant to Evusheld and bebtelovimab, according to the National Institutes of Health.

Evusheld is an antibody cocktail administered as two injections that people ages 12 and older with moderately or severely compromised immune systems take to prevent Covid-19. Bebtelovimab is a monoclonal antibody taken to treat Covid after an infection.

Biden urged people with weak immune systems to consult their physicians on what precautions to take. Dr. Ashish Jha, head of the White House Covid task force, said the U.S. is running out of options to treat the vulnerable because Congress failed to pass more money for the nation’s Covid response.

“We had hoped that over time as the pandemic went along, as our fight against this virus went along, we would be expanding our medicine cabinet,” Jha told reporters this week. “Because of lack of congressional funding that medicine cabinet has actually shrunk and that does put vulnerable people at risk.”

It’s unclear how well the new boosters will protect against variants such as BQ.1 and BQ.1.1. Jha has said the boosters should offer better protection than the old shots because these subvariants are descended from BA.5, which is contained in the updated vaccines.

Two independent studies from Columbia and Harvard this week found that the omicron boosters did not perform much better than the old shots against BA.5. The Food and Drug Administration said the studies were too small to draw any definitive conclusions.

The CDC, the FDA and the White House Covid taskforce believe the new shots will prove more effective because they are better matched to the circulating variants than the first generation vaccines.

“It is reasonable to expect based on what we know about immunology and the science of this virus that these new vaccines will provide better protection against infection, better protection against transmission and ongoing and better protection against serious illness,” Jha told reporters in September.

Jha called for all eligible Americans to get the omicron booster and their flu shot by Halloween so that they are protected when families start gathering for the holidays.