claim: three reasons covid-19 is less severe in younger age groups.
evidence_1: ludvigsson, j. f. systematic review of covid19 in children shows milder cases and a better prognosis than adults.", "because children have lower susceptibility and exhibit more mildly symptomatic cases for covid-19, school closures were slightly more effective at reducing transmission of covid-19 when the infectiousness of subclinical infections was assumed to be high.")