A large nationwide study has found important differences between the two major ways children have become seriously ill from the coronavirus. The findings may help doctors and parents better recognize the disease and understand more about the children who are at risk for either condition.
The study, published Wednesday in JAMA, analyzed 1,116 cases of young people who were treated at 66 hospitals in 31 states between March 15 and Oct. 31, 2020. About half the patients in the study had acute Covid-19, the predominantly lung-related illness that afflicts most adults who get sick. The rest had the inflammatory syndrome that has emerged in some children weeks after an initial infection that typically was mild.
The researchers found some similarities, but also significant differences, in the symptoms the two groups experienced and in the characteristics of the patients, who ranged in age from infants to 20-year-olds.
Young people with the syndrome, called Multisystem Inflammatory Syndrome in Children or MIS-C, were more likely to be between 6 and 12; more than 80 percent of the patients with acute Covid-19 were either younger than 6 or older than 12.
More than two-thirds of patients with either condition were Black or Hispanic, which experts say probably reflects the fact that those groups have been exposed disproportionately to the virus for socioeconomic and other reasons. But while Hispanic young people seemed to be at equal risk of developing either condition, Black children appeared to be at greater risk for developing the inflammatory syndrome than the acute illness, according to Dr. Adrienne Randolph, a pediatric critical care specialist at Boston Children’s Hospital and the senior author of the study.
“That MIS-C kids tended to be between 6 and 12 and Black either speaks to who’s getting infected more broadly, or maybe some true phenomenon about which age and ethnicity is most susceptible to MIS-C or protected from severe acute Covid,” said Dr. Srinivas Murthy, an associate professor of pediatrics at the University of British Columbia, who was not involved in the study.
The researchers found that young people with the inflammatory syndrome were much more likely to have been previously healthy than those with acute Covid were. Still, more than one-third of patients with acute Covid had no previous underlying condition. “It’s not like previously healthy kids are completely scot-free here,” Dr. Randolph said.
Young people with the inflammatory syndrome were more likely to need treatment in an intensive care unit, and their symptoms were much more likely to include heart problems and inflammation and to involve the skin and mucous membranes, than the patients with acute Covid were. But roughly the same proportions of patients with each condition needed respiratory support, including ventilators, and roughly the same small number of patients in each group died — 10 young people with MIS-C, and eight with acute Covid.