Solving the mystery of how the coronavirus impacts children has gained sudden steam, as doctors try to determine if there’s a link between COVID-19 and kids with a severe inflammatory illness, and researchers try to pin down their contagiousness before schools reopen.

Driving the news: New York hospitals have reported 73 suspected cases with two possible deaths from the inflammatory illness as of Friday evening.

Symptoms for young patients up to 21 years old, experiencing what doctors are calling “pediatric multisystem inflammatory syndrome,” include:

• Persistent fever and inflammation
• Abnormal, sudden or rapid heart rhythm
• Rash
• Diarrhea
• Weak pulse and rapid breathing
• Dizziness or loss of consciousness

Doctors have described children “screaming from stomach pain” while hospitalized for shock, Jane Newburger of Boston Children’s Hospital told the Washington Post.

• In some, arteries in their hearts swelled, similar to Kawasaki disease, a rare condition most often seen in infants and small children that causes blood vessel inflammation, she said.
• Researchers remain uncertain if this is being caused by COVID-19, but most children appear to have a link. Some affected children have tested positive for coronavirus antibodies, suggesting that the inflammation is “delayed,” Nancy Fliesler of Boston Children’s Hospital wrote on Friday.

What’s happening: More information is trickling in from various places.

• In New York City, some children required cardiac support, over half required mechanical ventilators, and most required blood pressure support, the city’s health department said Monday. The state issued an an advisory on Tuesday.
• Doctors in the U.K. reported a rise in April of these symptoms among children, some of whom tested positive for the coronavirus, the country’s Pediatric Intensive Care Society said in late April, citing an alert from the NHS. The Lancet published a report earlier this week detailing a cluster of cases.
• The Los Angeles Children’s Hospital had diagnosed three children with the inflammatory syndrome as of Friday. Doctors there say the syndrome is not contagious.
• In Delaware, a few cases have occurred over the last few months, a cardiologist with Nemours Children’s Health System told a local NPR affiliate station on Friday.
• Most affected children have responded well to treatment, the WashPost reports.

“I’m thinking of it kind of like the tip of the iceberg,” Jane Burns, a professor of pediatrics at the UC San Diego School of Medicine, told the WashPost. “There’s this very small number of patients, thankfully, who are presenting with this shock syndrome.”

The big picture: Early studies from China and the U.S. show that while children of all ages are at risk for the coronavirus, they are experiencing milder complications from the disease than adults, per the Centers for Disease Control and Prevention.

• Adults over 65 are most frequently hospitalized compared to other age groups, the CDC’s latest surveillance report shows.
• Children with the virus are less likely to be hospitalized or show symptoms, such as fever, cough or shortness of breath, the CDC found last month.

But, but, but: Two recent papers, while not definitive, offer evidence that children can transmit the virus.

• A report published in the journal Science found that while children have lower infection rates, they have three times as many contacts as adults and about as many opportunities to become infected.
• A study in Germany, which was not yet peer-reviewed, found that infected children carry at least as much virus as adults, and in some instances, more.

What’s next: The CDC is funding a $2.1 million study of 800 children who have been hospitalized after testing positive for the coronavirus through Boston Children’s Hospital. The study aims to understand why some children are more vulnerable to the disease.

• New York’s city and state health departments have urged all hospitals to immediately report cases of the syndrome.

Go deeper: The coronavirus is a moving target for efforts to tackle it