Enlarge / Revelers celebrate New Year’s Eve in Times Square on January 1, 2023, in New York City. This year's New Year's Eve returned to pre-COVID-19 pandemic numbers, with around 1 million people estimated to fill Times Square. (credit: Getty | Alexi Rosenfeld )

A new omicron coronavirus subvariant dubbed XBB.1.5 now accounts for an estimated 40.5 percent of all US COVID-19 cases amid a winter wave that is driving up hospitalizations, particularly in places where XBB.1.5 is most prevalent.

Nationwide, new reported cases are hovering around 59,000 per day, which is still relatively low compared with previous waves. But case data has become murkier over the 3-year-old pandemic, with fewer testing sites available now and the results of common at-home tests going unreported. Additionally, data reporting generally lags around end-of-year holidays, meaning case reports may jump in the coming days as backlogged data rolls in.

Hospitalizations, however, are clearly rising, with an average of around 45,000 hospitalized per day, according to data tracking by The New York Times. National hospitalization rates now rival those from the peak over this past summer driven by bygone omicron subvariants, federal data shows. Some of the areas seeing the large upticks in hospitalizations are those where the new subvariant, XBB.1.5 is most prevalent. For instance, in the Northeast (federal health region 1), XBB.1.5 has the highest regional proportion, accounting for 75 percent of cases, and hospitalizations have risen 16 percent over the prior seven days, the largest region-specific rise, according to data from the Centers for Disease Control and Prevention.