Epidemiology(47) COVID-19(30) children(22) Virology(18) 95% CI(17) SARS-CoV-2(14) pandemic(13) Infection(12) varicella(12) Patient(11) communicable diseases(10) Health services research(9) cohort study(8) Support(8) Spain(8) child health(8) enrolled(8) incidence(8) outcome(8) risk(8) healthcare(7) paediatrics(7) Cohort(7) SARS-COV-2 infection(7) Prophylaxis(7) changes in(7) incidence rate(7) SARS-CoV-2 antibodies(7) Result(7) adolescent health(6)