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In adults, the delta variant is reported to be more transmissible than the alpha variant, with a 2·26-times higher risk of hospitalization. Children have a significantly lower risk of severe disease, hospitalization, or death due to COVID-19 than adults. There are, however, little data on disease severity in children infected with different variants. The COVID Symptom Study (Zoe App) reported similar symptom burden (median four symptoms vs five symptoms), illness duration (median 5 days for both variants), and hospitalization (2·0% vs 2·2%) in a small cohort of 694 and 706 children aged 5–17 years infected with the alpha and delta variants, respectively. This study undertaken in England compares hospitalization and fatality rates in a national cohort of children (aged ≤15 years) with genotype-confirmed SARS-CoV-2 infection due to the alpha or delta variants over a 9-month period when the two variants caused sequential pandemic waves in England.
In conclusion, the low hospitalization rates in children with alpha and delta variant infections confirmed by genotyping should reassure parents, clinicians, and policymakers of the low risk of severe COVID-19 in children. Delta variant infections have, however, resulted in more childhood hospitalizations than alpha. Further studies are needed to distinguish between incidental infections and hospitalization for severe COVID-19, especially in children, where the former is common, and the latter is rare. COVID-19 vaccines have been shown to reduce the risk of hospitalization and severe COVID-19 in adults and adolescents. Similar studies are needed to assess the risk of severe COVID-19 in children infected with more recent and emerging variants.