A new study from Children's National Hospital in Washington, D.C., found that patients with multisystem inflammatory syndrome in children — a rare but serious immune response linked to COVID-19 — had more severe illness during the second wave of patients compared to the first wave.
The cohort study, published Nov. 2 in The Pediatric Infectious Disease Journal, included 106 patients treated for MIS-C at Children's National Hospital between March 2020 and April 2021. The first wave of patients were hospitalized between March and October 2020, and the second wave of patients were hospitalized between November 2020 and April 2021. The hospital saw 43 children during its first wave and 63 children during the second wave.
Compared to the first wave, children seen during the more recent wave had more frequent shortness of breath and required more advanced respiratory and inotropic support, the findings showed. The second wave cohort also had a higher proportion of children ages 15 and older, and a fewer number of children who tested positive for SARS-CoV-2.
At the same time, researchers did not find significant differences in cardiac outcomes or length of stay between the two cohorts.
"We've now seen three distinct waves of MIS-C since the beginning of the pandemic, each wave following national spikes in cases," said Roberta DeBiasi, MD, study author and chief of the division of pediatric infectious diseases at Children's National. "Kids in the second wave cohort had potentially experienced intermittent and/or repeated exposures to the virus circulating in their communities. In turn, this may have served as repeated triggers for their immune system, which created the more severe inflammatory response."
Additionally, the new findings supported earlier research that found Black and Hispanic children are disproportionately affected by MIS-C. Of the 106 children in this study, 54 percent were Black and 39 percent were Hispanic, researchers said.