medwireNews: US estimates suggest that 0.03% of SARS-CoV-2 infections lead to multisystem inflammatory syndrome in children (MIS-C), but rates vary by age and race/ethnicity, shows a report published in JAMA Network Open.
The study, based on data from two enhanced US surveillance systems (one passive and one active), revealed that 248 cases of MIS-C were reported in people younger than 21 years of age with current or recent SARS-CoV-2 infection between April and June 2020.
These individuals had a median age of 8 years, were slightly more often male (53.6%) than female, and were more likely to be Black (30.2%) or Hispanic or Latino (38.7%) than White (13.7%).
Angela Campbell (Centers for Disease Control and Prevention, Atlanta, Georgia) and co-investigators calculated that the overall incidence of MIS-C during the study period was 5.1 cases per 1,000,000 person–months.
However, when compared with White individuals, the adjusted incidence rates were a significant 9.26 times higher in Black people (9.6 vs 1.0 per 1,000,000 person–months), 8.92 times higher in Hispanic or Latino people (9.3 per 1,000,000 person–months), and 2.94 times higher in Asian or Pacific Islander people (3.1 per 1,000,000 person–months).
By age, the incidence was highest among children aged 6–10 years, followed by those aged 5 years and younger, those aged 11–15 years, and those aged 16–20 years, at 6.3, 4.9, 3.8, and 2.4 cases per 1,000,000 person–months, respectively.
When the researchers analyzed the data against the total number of COVID-19 cases, the incidence of MIS-C was 316 cases per 1,000,000 SARS-CoV-2 infections or 0.03%.
Again, the rates were significantly higher in Black, Hispanic or Latino, and Asian or Pacific Islander people than in White people, with adjusted incident rate ratios (aIRRs) of 5.62, 4.26, and 2.88, respectively. The corresponding adjusted incidence rates were 616, 467, 315, and 110 cases per 1,000,000 SARS-CoV-2 infections.
In this analysis, 11–15-year olds had a significant 50% lower MIS-C adjusted incidence rate than those aged 5 years and under (224 vs 444 cases per 1,000,000 SARS-CoV-2 infections). The incidence was lower still in the 16–20 years category, at 164 cases per 1,000,000 SARS-CoV-2 infections, corresponding to a significant 63% lower risk relative to the youngest children.
Conversely, the rate was higher, although not significantly so, in the children aged 6–10 years, at 613 cases per 1,000,000 SARS-CoV-2 infections, giving an aIRR of 1.38 compared with the group aged 5 years and younger.
Campbell and co-authors conclude: “The estimates and approach in this study provide baseline data prior to implementation of interventions, such as SARS-CoV-2 vaccination for children, allowing for subsequent monitoring of MIS-C as an outcome, as prevention of SARS-CoV-2 infection would be expected to reduce incidence of MIS-C.”
They add: “Our findings of higher incidence among younger children and among Hispanic or Latino, Black, and Asian or Pacific Islander persons emphasize a need for further study of risk factors for MIS-C.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group
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