Newly dominant variant more likely to evade Covid-19 antibodies, but so far not seen as more likely to cause serious disease

With a new subvariant of the novel coronavirus now dominant in the U.S., vaccinated people may be more likely to develop Covid-19 but still be well protected from serious disease, according to preliminary reports.

The XBB.1.5 subvariant “has raised concerns about another potential wave of Covid cases following the busy holiday travel season” but “There’s no indication it causes more severe illness than any other omicron virus, Dr. Barbara Mahon, director of CDC’s Coronavirus and Other Respiratory Viruses Division, told NBC News. . . . The CDC projected Friday that about 40% of confirmed U.S. Covid cases are caused by the XBB.1.5 strain, up from 20% a week ago.”

XBB.1.5 is so new that research on it is very limited, but researchers from Columbia University recently reported in the journal Cell that sublineages of the BQ and XBB subvariants had a “dramatically increased” ability to evade antibody protection, even among those who had received the current bivalent booster. “However, it is important to emphasize that although infections may now be more likely, Covid-19 vaccines have been shown to remain effective at preventing hospitalization and severe disease even against Omicron as well as possibly reducing the risk of post-acute sequelae of Covid-19 (PASC, or long Covid),” the researchers reported.