NEWARK, N.J. (CBSNewYork) — A rare illness linked to COVID-19 is reappearing in children this winter.

In many cases, this illness is more severe than what doctors treated during the first wave in the spring, but CBS2’s Hazel Sanchez found that doesn’t hold true state to state.

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Thirteen-year-old Alana Tucker, of Newark, is back to being a typical teenager, but she had a frightening health scare in May when she was hospitalized with COVID-19 then developed a rare condition, multisystem inflammatory syndrome in children, also known as MIS-C.

“It felt terrible,” Alana said. “I felt like I couldn’t make it.”

The illness generally appears in young patients weeks after they’re infected with the coronavirus. Symptoms include fever and rash. They could escalate to heart dysfunction and could prove fatal.

Now, doctors across the country, including Dr. Sivia Lepidus at Hackensack University Medical Center, are seeing more severe cases of MIS-C compared to last spring.

“We have seen more critically ill patients with MIS-C overall. We have needed to use more aggressive therapy,” she said.

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But it’s a different story across the Hudson River at New York Presbyterian — Morgan Stanley Children’s Hospital, where Dr. Steve Kernie specializes in pediatric critical care.

“We’re not seeing big surges in New York. Not surprisingly, we are seeing a few more cases than we saw a few months ago, but it is treatable. The cases we’re seeing are not terribly severe, and by and large, the kids do very well,” he said.

Lepidus believes the difference may be the strict COVID-19 restrictions in New York City, where mask-wearing is more prevalent. Masks not only prevent transmission but also reduce the viral load.

“The kids who do have multisystem inflammatory syndrome in children… Frequently, there’s a lot of COVID in the family, they were exposed to it, and maybe they had multiple families with it. Maybe they were with a prolonged period of time without masks,” Lepidus said. “And I wonder if that’s happening more in New Jersey.”

Doctors say there is discussion new COVID variants could also be causing more severe cases of MIS-C, but it’s too soon to tell.

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Until more research is done, doctors say the best way to prevent MIS-C is to protect against COVID-19.