A Rady Children's Hospital patient who contracted COVID-19 also tested positive for multisystem inflammatory syndrome in children (MIS-C), a rare disease being investigated for its connection to the novel coronavirus in children.
MIS-C, formerly called Pediatric Inflammatory Multisystem Syndrome (PIMS), has been described by medical experts as a "mystery" illness linked to COVID-19.
A spike in MIS-C cases corresponded with a rise in novel coronavirus infections at the onset of the pandemic, leading doctors around the nation to test MIS-C patients for coronavirus antibodies which could signify they had contracted that virus first.
A spokesperson for Rady Children's said a 6-year-old COVID-19 patient contracted MIS-C. It's the first and only MIS-C case at the facility so far, the spokesperson said.
The child was admitted late last week and had already been released by Thursday afternoon, according to the spokesperson.
The Centers for Disease Control and Prevention issued a health alert to physicians in mid-May about the deadly disease that has appeared in multiple states and claimed the lives of children as young as 5 and as old as 18.
Doctors and researchers across the country believe MIS-C and COVID-19 are somehow linked, but are still trying to uncover evidence solidifying their connection.
Now that MIS-C is garnering more attention from medical experts, Rady Children's said they are examining COVID-19 cases that have come through their facility to see if the patients also had MIS-C, the spokesperson said.
Doctors who've treated MIS-C cases have said the illness mirrors many of the symptoms of Kawasaki disease which researchers are also investigating for its possible connection to COVID-19 in children.
"What we need is information,” Dr. Adiana Tremoulet, associate director of the Kawasaki Research Center at Rady Children’s Hospital, told NBC 7 earlier this month. “What we don't need is fear right now."
A California baby was the first patient linking COVID-19 to Kawasaki disease, according to the San Francisco Chronicle.
MIS-C and Kawasaki disease are hyper-inflammatory diseases that can affect children of any age and, if left untreated, can trigger heart failure.
The CDC's alert underscores how little researchers still know about the coronavirus -- just months ago, health experts said it didn't affect children.
"There may be a link there with the virus both with general Kawasaki disease as well as [MIS-C],” says Tremoulet.
Tremoulet says many children in the hospital with MIS-C were exposed to family members infected with COVID-19.
"We're certainly not trying to sound the alarm,” Tremoulet said. “We're just trying to educate so our families know when they should seek medical attention."
Kawasaki symptoms include fever, rash, red-eye, swollen hands and feet, and red lips and tongue. MIS-C is similar, but can also include severe abdominal pain and low blood pressure.