The New York State Department of Health says the XBB 1.5 subvariant of COVID-19 makes up over 50% of cases in the state.

The World Health Organization says it's the most transmissible form of omicron to date.

In December alone, it went from causing about 4% of infections in the U.S. to 41%. 

 Dr. Ashish Jha, the White House COVID-19 response coordinator, says that's a quick increase. 

“First of all, this is a new emerging subvariant, and it has risen very quickly across the country. It's gone from being almost non-existent a month ago to now making up a large portion of all the infections, and that increase is very very fast,” she said. 

There are 580 COVID cases in Nassau and 618 in Suffolk. The seven-day positivity rate for Long Island is 9.66%.