Each new variant of concern that rises to dominance changes what we know about the COVID-19 virus. At the beginning of the pandemic, children were believed to be immune to symptomatic COVID-19 infection, but this was disproved by the emergence of highly virulent strains.
The symptoms and severity of COVID-19 disease are as changeable as the virus itself. One study, published in JAMA Network Open, examined whether variant type alters the symptom profiles of children infected with COVID-19.
The multicenter cohort study evaluated children in Canadian tertiary care emergency departments. The pediatric patients presented at 1 of 14 urban emergency departments between August 4, 2020-February 22, 2022.
Of the 7272 pediatric patients who presented to an emergency department, 19.8% (n = 1440) tested positive for COVID-19 and were included in this study. The cohort was 55.6% male (n = 801), and the average age was 2.0 years. Children were excluded if they were diagnosed with Kawasaki disease or multisystem inflammatory syndrome of children (MIS-C).
The primary outcomes were presence and number of COVID-19 symptoms. Secondary outcomes included presence of core COVID-19 symptoms, chest radiography findings, treatments, and 14-day outcomes.
Children infected with the Alpha variant reported the fewest core COVID-19 symptoms (195 of 237; 82.3%). The most core COVID-19 symptoms were reported by children infected with Omicron (434 of 468; 92.7%).
In a multivariable model with the original, wild-type Wuhan COVID-19 strain as the referent, the Omicron and Delta variants were more strongly correlated with fever and cough. Upper respiratory tract symptoms were associated with Delta, while lower respiratory tract and systemic symptoms were associated with Omicron.
Chest radiography and subsequent treatment were most frequent in children who contracted the Omicron variant. Omicron pediatric infections were also more likely to require intravenous fluids, corticosteroids, and emergency department visits.
The findings of this prospective observational cohort study suggest the Omicron variant caused more severe symptoms in children than other COVID-19 variants. Notably, the proportions of children admitted to the hospital and intensive care unit did not differ between variants.