Fast-spreading COVID subvariant responsible for more than 50% of new cases, state says

The fast-spreading XBB.1.5 subvariant is now responsible for more than 50% of new COVID-19 cases in New York, state health officials said Friday. 

Early data shows the subvariant spreads more rapidly than other strains currently circulating, though it doesn’t appear to cause more severe COVID-19 disease.

Experts said the latest group of subvariants, including XBB.1.5, can cause COVID-19 infections even in people who are vaccinated or recently tested positive. But they added the COVID-19 vaccine continues to protect people against severe forms of the disease and hospitalization.

“We continue to experience different variants working their way through our communities,” said Dr. David Hirschwerk, medical director of North Shore University Hospital and an infectious disease expert.

“For the most part, it’s been a similar theme, where the new variants emerge that overtake the other variants for the most part,” he said. “The strains have been contagious and led to high rates of COVID-19 in our communities, but fortunately has not led to a significant increase in people who are severely ill related to COVID-19.”

COVID-19 is caused by the SARS-CoV-2 virus, which has continued to mutate since first discovered in December 2019. The omicron variant, which was more contagious than the original form of the virus, emerged a little more than a year ago, leading to a surge in cases and hospitalizations. XBB.1.5 is a subvariant of omicron.

Officials at Northwell Health, the largest health care system in the state with 10 hospitals on Long Island, said XBB.1 and XBB.1.5 made up 69.7% of COVID-19 in its system as of Jan. 4

Hospitalizations of COVID-19 patients across Northwell's system have also steadily ticked up, from 476 cases on Nov. 3 to 545 cases on Dec. 3 and 783 cases on Jan. 3.

However, hospitalizations are still markedly lower than during last year’s omicron surge, when there were 1,589 cases as of Jan. 3, 2022.

More than 6,200 COVID-19 positive test results were recorded by the state for Jan. 4 and 5, according to the state website. The 7-day average percentage of positive test results for the state was 8.58%, and higher on Long Island at 9.66%. But the actual number of COVID-19 cases across the state is likely much higher since people who test at home are not required to report the results.

XBB.1.5 has quickly edged out the former dominant subvariants BQ.1 and BQ.1.1. As of Dec. 17, XBB.1.5 made up 27.6% of new cases and by Dec. 31 it was 51.9%.

Meanwhile, BQ.1 dropped to 10.6% of new cases by Dec. 31 and B.Q.1.1 now makes up just 16.4% of new cases.

Hirschwerk said because XBB.1.5 appears to be more contagious than other circulating strains, it is outcompeting them.

“That’s why there is more of it in the community at this point,” he said.

Acting State Health Commissioner Dr. James McDonald urged eligible New Yorkers who have not yet received the updated COVID-19 booster shot to do so.

“The booster provides significant protection against getting very sick or being hospitalized, and according to the latest data from CDC, those who received the bivalent booster were more than 18 times less likely to die from COVID-19 compared to unvaccinated people,” he said in a statement.

By Lisa L. Colangelo

lisa.colangelo@newsday.com@lisalcolangelo

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.