Dynamics of COVID-19 Symptoms among Children Infected with SARS-CoV-2

Objectives: To compare symptom dynamics in children infected with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) between the third and fourth waves of the pandemic in Israel, dominated by the Alpha and Delta variants, respectively.
Methods: Our cohort included all children and adolescents, members of the second-largest Health Maintenance Organisation (HMO) in Israel that had positive real-time polymerase chain reaction (RT-PCR) test during the third and fourth waves of the pandemic (December 1, 2020 - April 30, 2021, and June 1, 2021 - October 10, 2021, respectively) and for whom their primary physician filled-in a symptom questionnaire.
Results: A total of 32,485 and 44,130 children and adolescents in the third and fourth waves were included in the final analysis. The rate of children with symptomatic disease among patients with documented SARS-CoV-2 infection was higher in the fourth wave compared to the third wave (49.9% vs. 37.5%). The most commonly reported symptom and the only symptom that substantially (SMD=0.47) differed between waves was fever, with 33% of SARS-CoV-2 infected children in the fourth wave vs. 13.6% in the third wave. The rates of respiratory, neurology and gastrointestinal symptoms did not differ between waves. Preschool children had the lowest prevalence of febrile illness compared to other age groups.
Conclusions: Children and adolescents infected during the fourth wave of the pandemic in Israel, a Delta-dominant period, had a significantly higher rate of symptomatic febrile illness than the Alpha-dominant period. This phenomenon occurred across all age groups.