Incidence of Multisystem Inflammatory Syndrome in Children Among US Persons Infected With SARS-CoV-2

Payne, Amanda B.; Gilani, Zunera; Godfred-Cato, Shana; Belay, Ermias D.; Feldstein, Leora R.; Patel, Manish M.; Randolph, Adrienne G.; Newhams, Margaret; Thomas, Deepam; Magleby, Reed; Hsu, Katherine; Burns, Meagan; Dufort, Elizabeth; Maxted, Angie; Pietrowski, Michael; Longenberger, Allison; Bidol, Sally; Henderson, Justin; Sosa, Lynn; Edmundson, Alexandra; Tobin-D’Angelo, Melissa; Edison, Laura; Heidemann, Sabrina; Singh, Aalok R.; Giuliano, John S.; Kleinman, Lawrence C.; Tarquinio, Keiko M.; Walsh, Rowan F.; Fitzgerald, Julie C.; Clouser, Katharine N.; Gertz, Shira J.; Carroll, Ryan W.; Carroll, Christopher L.; Hoots, Brooke E.; Reed, Carrie; Dahlgren, F. Scott; Oster, Matthew E.; Pierce, Timmy J.; Curns, Aaron T.; Langley, Gayle E.; Campbell, Angela P.; Balachandran, Neha; Murray, Thomas S.; Burkholder, Cole; Brancard, Troy; Lifshitz, Jenna; Leach, Dylan; Charpie, Ian; Tice, Cory; Coffin, Susan E.; Perella, Dana; Jones, Kaitlin; Marohn, Kimberly L.; Yager, Phoebe H.; Fernandes, Neil D.; Flori, Heidi R.; Koncicki, Monica L.; Walker, Karen S.; Di Pentima, Maria Cecilia; Li, Simon; Horwitz, Steven M.; Gaur, Sunanda; Coffey, Dennis C.; Harwayne-Gidansky, Ilana; Hymes, Saul R.; Thomas, Neal J.; Ackerman, Kate G.; Cholette, Jill M.

IMPORTANCE: Multisystem inflammatory syndrome in children (MIS-C) is associated with recent or current SARS-CoV-2 infection. Information on MIS-C incidence is limited. OBJECTIVE: To estimate population-based MIS-C incidence per 1 000 000 person-months and to estimate MIS-C incidence per 1 000 000 SARS-CoV-2 infections in persons younger than 21 years. DESIGN, SETTING, AND PARTICIPANTS: This cohort study used enhanced surveillance data to identify persons with MIS-C during April to June 2020, in 7 jurisdictions reporting to both the Centers for Disease Control and Prevention national surveillance and to Overcoming COVID-19, a multicenter MIS-C study. Denominators for population-based estimates were derived from census estimates; denominators for incidence per 1 000 000 SARS-CoV-2 infections were estimated by applying published age- and month-specific multipliers accounting for underdetection of reported COVID-19 case counts. Jurisdictions included Connecticut, Georgia, Massachusetts, Michigan, New Jersey, New York (excluding New York City), and Pennsylvania. Data analyses were conducted from August to December 2020. EXPOSURES: Race/ethnicity, sex, and age group (ie, ≤5, 6-10, 11-15, and 16-20 years). MAIN OUTCOMES AND MEASURES: Overall and stratum-specific adjusted estimated MIS-C incidence per 1 000 000 person-months and per 1 000 000 SARS-CoV-2 infections. RESULTS: In the 7 jurisdictions examined, 248 persons with MIS-C were reported (median [interquartile range] age, 8 [4-13] years; 133 [53.6%] male; 96 persons [38.7%] were Hispanic or Latino; 75 persons [30.2%] were Black). The incidence of MIS-C per 1 000 000 person-months was 5.1 (95% CI, 4.5-5.8) persons. Compared with White persons, incidence per 1 000 000 person-months was higher among Black persons (adjusted incidence rate ratio [aIRR], 9.26 [95% CI, 6.15-13.93]), Hispanic or Latino persons (aIRR, 8.92 [95% CI, 6.00-13.26]), and Asian or Pacific Islander (aIRR, 2.94 [95% CI, 1.49-5.82]) persons. MIS-C incidence per 1 000 000 SARS-CoV-2 infections was 316 (95% CI, 278-357) persons and was higher among Black (aIRR, 5.62 [95% CI, 3.68-8.60]), Hispanic or Latino (aIRR, 4.26 [95% CI, 2.85-6.38]), and Asian or Pacific Islander persons (aIRR, 2.88 [95% CI, 1.42-5.83]) compared with White persons. For both analyses, incidence was highest among children aged 5 years or younger (4.9 [95% CI, 3.7-6.6] children per 1 000 000 person-months) and children aged 6 to 10 years (6.3 [95% CI, 4.8-8.3] children per 1 000 000 person-months). CONCLUSIONS AND RELEVANCE: In this cohort study, MIS-C was a rare complication associated with SARS-CoV-2 infection. Estimates for population-based incidence and incidence among persons with infection were higher among Black, Hispanic or Latino, and Asian or Pacific Islander persons. Further study is needed to understand variability by race/ethnicity and age group.