New coronavirus subvariant, XBB, now widespread in New England

The subvariant now accounts for more than 50% of all cases in New England.

A healthcare professional holds a vial of the latest COVID-19 booster. Rogelio V. Solis/Associated Press

COVID-19 continues to spread in New England, and now a new subvariant that could be better at dodging immunity is the dominant form of the virus in the region. 

The subvariant, known as XBB, accounted for about 52.6% of all cases in New England during the period of time between Dec. 18 and Dec. 24, according to CDC data. The week before, it accounted for about 34.3% of cases in the region, and just 20% earlier in December. 

This quick spread likely means that XBB is particularly good at evading the immunity people have acquired from vaccinations and prior infections. 

“It looks like it’s just going to blow the other ones away in a very short period,” Jeremy Luban, professor of molecular medicine, biochemistry, and molecular biotechnology at UMass Chan Medical School, told The Boston Globe. “The most likely explanation is that it’s more transmissible.” 


The XBB subvariant is also spreading nationwide. For the week ending on Dec. 24, it accounted for 18.3% of all cases throughout the country. The week before, XBB accounted for 11.2%, according to CDC Data. 

XBB is an omicron subvariant. The omicron variant has been pummeling the country since last fall, and has been churning out multiple subvariants like BA.5 and BQ.1.1.

“I think it’s like we’ve been seeing essentially since last December or January, that subvariants of omicron continue to emerge,” Daniel Kuritzkes of Brigham and Women’s Hospital told NBC10 Boston. “Each one that replaces the previous one is doing so either because it is more transmissible or because it is able to evade the immune response generated by the previous variant, which is more or less what viruses tend to do overall.”

Although more research must still be done on XBB, the WHO said in October that XBB did not seem to substantially lead to more severe infections. The group did acknowledge that early evidence pointed to XBB posing a higher reinfection risk than other Omicron subvariants.  

Health professionals are continuing to urge members of the public to get vaccinated and keep up with their latest boosters. The most recent booster protects against omicron and the original virus strain, according to a recent study published in The New England Journal of Medicine.


“The biggest thing that is going to be driving hospitalizations right now is individuals that have waning immunity,” Andrew Pekosz, a professor of molecular microbiology and immunology at the Johns Hopkins University Bloomberg School of Public Health, told the Globe. “You really need to have a recent booster, ideally the bivalent booster, because that’s what’s going to give you more protection, especially from hospitalization.”


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