Pediatricians have a new warning for parents about a syndrome they say is connected to the coronavirus.

MIS-C, or Multi System Inflammatory Syndrome, is an overactive immune response to the COVID virus where different body parts like the heart and lungs become inflamed.

There have been 646 cases of MIS-C so far, with three children having died from it. Dr. John Zaso tells News 12 it occurs in some kids who had COVID and then later develop MIS-C a few weeks later. A total of 95% of children who develop MIS-C are unvaccinated.

"It's a disease that can cause problems and why take a chance? You're playing Russian roulette," said Zaso.

This latest development comes on the heels of Gov. Kathy Hochul on Friday saying if more children get vaccinated against COVID-19, it may speed up the timeline for dropping a statewide mandate for masks inside schools which is set to expire Feb. 21.

The CDC says close to 70% of children ages 12 to 17 on Long Island got the vaccine, but only 24% of 5- to-11-year-olds are vaccinated. Kids ages 2-5 continue to wait to be eligible for the vaccine.

"The more children we have vaccinated, the safer they'll be when they go to school…They won't need a mask anymore which we are striving for, but we're not there yet," Hochul said.

Experts don't think that dropping mask mandate by Feb. 21 is realistic, and instead believe that maybe it can happen by the spring or early summer when the weather turns warm and windows can be opened for ventilation.

The risk of MIS-C is 60 times higher for kids who are not vaccinated. Zaso says the disease is preventable.

"Three fatalities is not that high," he acknowledged. "They didn't need to die. And with the vaccine, while you still might get COVID and you might get a mild syndrome from it…We can tell you that the odds are overwhelming in your favor that if you get MIS-C, you're going to be in trouble. But if you're vaccinated, you don't have that issue."