Although coronavirus and dengue are different in many ways, Dr. Paniz-Mondolfi noticed several similarities. Both viruses target endothelial cells, which line blood vessels. With dengue, blood can slowly seep out of patients’ veins, causing shock and death; the coronavirus too, injures blood vessels throughout the body. With dengue, case reports have suggested that this blood vessel damage may trigger an exaggerated inflammatory response that can possibly lead to Kawasaki disease. Dr. Paniz-Mondolfi wondered if the same would happen with some children who have Covid-19 — that they may experience a similar dangerous post-infectious inflammatory syndrome. When viruses “hit the endothelium, there’s no good news,” he said. “I could not get Kawasaki out of my mind.”
Most children who catch the coronavirus only experience mild symptoms. But a few months after the coronavirus struck New York, Dr. Paniz-Mondolfi’s hospital began treating a small number of seriously ill children, most of whom had been infected with Covid-19 weeks earlier. The condition came to be known as multisystem inflammatory syndrome in children, or MIS-C. Kids with MIS-C usually have severe abdominal pain, high fevers, vomiting, diarrhea and sometimes sprawling rashes or bloodshot eyes. Often, they have to be hospitalized and can experience damage to multiple organs — characteristics immediately recognized as similar to Kawasaki disease.
As of September 3, 2020, the Centers for Disease Control and Prevention had received reports of 792 MIS-C cases in the United States and 16 deaths; 20 have been treated at Mount Sinai as of Aug. 27. Of those nearly 800 cases, more than 70 percent have been either Black or Latino. A C.D.C. study published in August found that the rate of hospitalization for Black children with Covid-19 is five times higher than it is for white children, and the rate for Latino children is eight times higher.
Faced with a deluge of MIS-C cases at Mount Sinai in May and June 2020, Dr. Paniz-Mondolfi and his colleague Mariawy Riollano-Cruz, M.D., a pediatric infectious disease physician at Mount Sinai, immediately noticed the racial discrepancies, as they reported in a study published in June. They wondered why. Perhaps the trend could be explained by the fact that communities of color have higher rates of Covid-19 than white communities do and more Covid-19 cases leads to more MIS-C cases.
But the math doesn’t fully add up, at least for Black children. In a systematic review published in August, C.D.C. researchers pointed out that about 20 percent of all of New York’s Covid-19 patients are Black, based on a survey of adults, but 40 percent of MIS-C patients are. Likewise, a national study looking at 186 patients found that 25 percent of MIS-C patients in the United States are Black, yet C.D.C. data suggest that only 19 percent of U.S. Covid-19 patients of all ages are (though race and ethnicity data are only available for about half of all cases reported to the C.D.C.). Among Latino children, the percentages match up more closely, but are still higher than expected.
Because access to testing is limited in minority communities, it may be that Black and Latino Americans are catching the coronavirus at higher rates than these test percentages suggest. If so, Black and Latino children may be developing MIS-C at rates that would be expected based on their exposure to Covid-19.