The first sign that something was wrong came with stomach pains. It was April 30, and 9-year-old Kyree McBride wasn't feeling well.
His mother, Tammie Hairston, thought it might have been something that he ate. But soon, young McBride was battling a 102-degree fever.
Worried he may have contracted the coronavirus, Hairston took her son to the hospital. "It was a quick in and out of the emergency room," she said. Doctors told her to take him home and monitor him.
The fever, though, didn't break. In a telemedicine call with McBride's doctor a few days later, Hairston was told to hang tight. Then the stomach pains came back, stronger this time. Then vomiting. Later, Kyree's skin began to develop a reddish hue.
By the time he was finally admitted to Children's National Hospital in Washington, D.C., more than a week later, doctors determined that although he was negative for COVID-19, he had developed antibodies for the coronavirus.
It was a sign he'd already been infected and recovered from COVID-19. And it mirrored what they had been seeing in dozens of young patients who since the start of the pandemic have been diagnosed with a condition known as Multisystem-Inflammatory Syndrome in Children, or MIS-C.
Since April, when cases of the syndrome were first detected in Europe, doctors have been puzzling over the mysterious new condition, one they're attributing to complications linked to COVID-19. While early research suggests the condition is rare, experts are still racing to answer even the most basic questions about the illness, such as why some children are more susceptible than others, how to safely treat it and what it might mean for their long-term health.
The connection to COVID-19
Throughout the coronavirus pandemic, young children have been the least likely of all age groups to become seriously ill with the virus, though they can still become infected and spread it.
When they do become infected, they often don't exhibit symptoms, making it nearly impossible for parents to know whether they have the coronavirus or may be at risk for MIS-C.
The majority of known cases have been concentrated on the East Coast. New York state has reported more than 150 cases. Washington has seen more than 30 cases, according to Children's National. Cases have also been reported in a handful of other states, including California, Louisiana, Mississippi and Washington state.
The youngest confirmed patient was just a few weeks old. At least four children — one in Louisiana and three in New York — are reported to have died from the condition.
"A new phenomenon for us"
Children's National has been one of the leading hospitals in the nation treating patients with MIS-C. Doctors there have seen 35 patients with the syndrome since the end of April, according to a hospital spokesperson. But the exact number has been difficult to pinpoint, in part because the condition is so new and because the diagnostic guidelines from the Centers for Disease Control and Prevention are still loosely defined.
"It's definitely a new phenomenon for us, and it definitely has a lot of implications that we are all quite concerned about," said Dr. Michael Bell, the chief of critical care medicine at Children's National.
Dr. Roberta DeBiasi, the hospital's chief of pediatric infectious diseases, says staff has seen the syndrome manifest itself in a variety ways.
The first, which has drawn the most attention, appears to mimic Kawasaki disease, an inflammatory illness that causes inflammation in the blood vessels, particularly the coronary arteries.
Patients showing these symptoms are "the most obvious type" of cases, said DeBiasi. "They may have very high fevers, red eyes, red lips, red tongue. They may have a rash over their body. They may have a swollen lymph node, swelling of their hands and feet."
In other cases, patients might exhibit "lots of inflammation," according to DeBiasi. Like McBride, they may also experience severe abdominal pain.
The many unknowns
The good news at Children's National is that they have not had a child die from MIS-C.
"We really have a way of ... identifying them early, treating them early so that kids don't get sicker," said Karen Smith, the chief of hospitalist medicine at Children's.
Despite that success, doctors are still trying to understand a key question about the condition: when children are getting it.
"Is this acute viral? Is this post-infectious? Is it a combination? We've got to figure this out in our patient cohort," DeBiasi said.
The majority of the hospital's MIS-C patients do not test positive for the coronavirus, yet they have the antibodies that signal they've recovered from the virus. That implies a post-infection response in which kids' immune systems are overreacting to the coronavirus after fighting off an active infection, DeBiasi said.
Doctors are also trying to figure out which children are getting MIS-C. Initially, there were no reported cases of the condition in China or on America's West Coast. One possible explanation for the regional disparity in the U.S., DeBiasi said, could stem from the theory that the West Coast was hit by a variant of the coronavirus from China, while the East Coast was hit by one from Europe
DeBiasi also wonders whether some kids, as with adult populations, are more vulnerable as a result of health disparities.
"There does seem to be more infection and severity in some of the racial or ethnic groups or perhaps even genetic predispositions," she said.
But she suspects the answer might be simpler. Children could be getting sick as a result of continued exposure to the coronavirus spreading in their community.
"I think what's happening here is these kids that are being re-exposed out in the community to a virus that they saw and made an appropriate immune response to, initially," she said, adding that now, "that immune response is just inappropriately revved up."
However, given the uncertainty, doctors at Children's say they are trying to be conservative when it comes to diagnosing MIS-C because the treatments involved can strain young, growing bodies.
There are also concerns about possible long-term risks from the illness.
The children with MIS-C who end up in critical care often have inflammation in their heart and in other organs, said Bell of the hospital's critical care division. He considers, as one example, the lifelong effects on a 5-year-old who has MIS-C.
"If she has some terrible swelling from it, which could be coronary arteries that get dilated, and might have heart attacks when she's 6, that's going to affect her for 70 years of life expectancy," he said. "Yes, fewer kids get this. Fewer kids get critically ill with it. But it's not like there's not a huge impact to child's health."
"I try to keep an eye on him"
Kyree McBride is feeling better, but he's still low energy. At a recent checkup, doctors gave him a heart monitor because his heart is arrhythmic.
Hairston, his mother, continues to frantically monitor him.
"I'm always feeling his head and making sure he don't have any more fevers and asking him, you know, every hour on the hour, 'Are you OK? Are you feeling OK? Let me feel your head,' " she said.
The hospital was a scary time for McBride, and she worries that he'll be hesitant to tell her if something else goes wrong.
"I try to keep an eye on him," Hairston said.
She advises other parents to be watchful, and, if in doubt, to take their child to the hospital.