October 17, 2022 4:27 PM EDT

With another potential COVID-19 surge looming, experts are turning their attention to a pair of new variants that are steadily spreading: BQ.1 and BQ.1.1.

Both BQ.1 and BQ.1.1 descended from BA.5, an Omicron subvariant that currently accounts for about 68% of COVID-19 cases in the U.S. But BA.5’s relatives are quickly gaining ground. BQ.1 and BQ.1.1 each accounted for 5.7% of new COVID-19 cases in the U.S. during the week ending Oct. 15, according to data from the U.S. Centers for Disease Control and Prevention (CDC). Combined, that’s about 11% of new cases nationwide. In New York and New Jersey, the total proportion was closer to 20%. A few weeks ago, these variants barely showed up on the CDC’s tracker, which suggests they’re able to spread fast.

Of the two, BQ.1.1 is more concerning, says Dr. Eric Topol, founder of the Scripps Research Translational Institute and a close watcher of COVID-19 research. Both have a number of mutations relative to BA.5, but BQ.1.1 is “just riddled with troublesome mutations” that could “pose a threat to our immune system’s response,” Topol says.

If there’s any good news about BQ.1 and BQ.1.1, it’s related to vaccination. The new Omicron-specific boosters were designed to target BA.4 and BA.5, and preliminary research suggests they stoke an effective immune response. Since BQ.1 and BQ.1.1 are both related to BA.5, the new shots will “almost certainly” provide some cross protection, White House medical adviser Dr. Anthony Fauci told CBS News. That’s yet another reason to get boosted, which less than 10% of eligible Americans have reportedly done so far.

It’s too soon to say exactly how the bivalent boosters will work against newer strains like these, but Topol encourages anyone eligible to get one. “That’s the best thing you can do right now to arm up against any of these new variants,” Topol says. “Just keep your immune system as primed and ready as possible.”

More research is needed about BQ.1 and BQ.1.1, but a study posted online in October (which has not yet been peer-reviewed) warned that “current herd immunity and BA.5 vaccine boosters may not provide sufficiently broad protection against infection” as the virus continues to evolve. The researchers found that BQ.1.1 is able to evade antibodies from past BA.5 infections, which suggests it may also be able to dodge protection from vaccines. The study also found that monoclonal antibody drugs—including Evusheld, which is used to protect people who are immunocompromised and do not respond well to COVID-19 vaccines—are less effective against BQ.1.1, compared to earlier strains of the virus. The U.S. Food and Drug Administration also recently warned health care providers that Evusheld may not neutralize all variants of SARS-CoV-2.

While vaccines and boosters are currently the best tools we have to fight COVID-19, the emergence of the BQ variants is further proof that they’re not enough to fully shield people from sickness. If an evasive variant like BQ.1 or BQ.1.1 spreads widely this winter, and some lines of defense are rendered less effective, other precautions like masking and avoiding crowded indoor areas may be necessary to protect against infection.

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Write to Jamie Ducharme at jamie.ducharme@time.com.

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