"For COVID" or "With COVID": Classification of SARS-CoV-2 Hospitalizations in Children

Pediatric hospitalization rates are used as a marker of coronavirus disease 2019 (COVID-19) disease severity in children but may be inflated by the detection of mild or asymptomatic infection via universal screening. We aimed to classify COVID-19 hospitalizations using an existing and novel approach and to assess the interrater reliability of both approaches.

This retrospective cohort study characterized severity of illness and likelihood of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection as the cause of hospitalization in pediatric patients <18 years of age. Subjects had positive SARS-CoV-2 nasopharyngeal testing or were diagnosed with multisystem inflammatory syndrome in children and were hospitalized between May 10, 2020 (when universal screening of all admissions began) and February 10, 2021, at a university-based, quaternary care children's hospital in Northern California. Hospitalizations were categorized as either likely or unlikely to be caused by SARS-CoV-2 (novel approach), and disease severity was categorized according to previously published classification of disease severity.

Of 117 hospitalizations, 46 (39.3%) were asymptomatic, 33 (28.2%) had mild to moderate disease, 9 (7.7%) had severe illness, and 15 (12.8%) had critical illness (weighted κ: 0.82). A total of 14 (12%) patients had multisystem inflammatory syndrome in children. A total of 53 (45%) admissions were categorized as unlikely to be caused by SARS-CoV-2 (κ: 0.78).

Although COVID-19 has considerable associated morbidity and mortality in children, reported hospitalization rates likely lead to overestimation of the true disease burden.