Approximately 3% of youth who tested positive for COVID-19 in an emergency department setting had severe outcomes after 2 weeks, but this risk was 0.5% among those not admitted to the hospital, based on data from more than 3,000 individuals aged 18 and younger.
In the early stages of the COVID-19 pandemic, youth younger than 18 years accounted for fewer than 5% of reported cases, but now account for approximately 25% of positive cases, wrote Anna L. Funk, PhD, of the University of Calgary, Alberta, Canada, and colleagues.
However, the risk of severe outcomes of youth with COVID-19 remains poorly understood and data from large studies are lacking, they noted.
In a prospective cohort study published in JAMA Network Open, the researchers reviewed data from 3,221 children and adolescents who were tested for COVID-19 at one of 41 emergency departments in 10 countries including Argentina, Australia, Canada, Costa Rica, Italy, New Zealand, Paraguay, Singapore, Spain, and the United States between March 2020 and June 2021. Positive infections were confirmed by polymerase chain reaction (PCR) testing. At 14 days’ follow-up after a positive test, 735 patients (22.8%), were hospitalized, 107 (3.3%) had severe outcomes, and 4 (0.12%) had died. Severe outcomes were significantly more likely in children aged 5-10 years and 10-18 years vs. less than 1 year (odds ratios, 1.60 and 2.39, respectively), and in children with a self-reported chronic illness (OR, 2.34) or a prior episode of pneumonia (OR, 3.15).
Severe outcomes were more likely in patients who presented with symptoms that started 4-7 days before seeking care, compared with those whose symptoms started 0-3 days before seeking care (OR, 2.22).
The researchers also reviewed data from a subgroup of 2,510 individuals who were discharged home from the ED after initial testing. At 14 days’ follow-up, 50 of these patients (2.0%) were hospitalized and 12 (0.5%) had severe outcomes. In addition, the researchers found that the risk of severe outcomes among hospitalized COVID-19–positive youth was nearly four times higher, compared with hospitalized youth who tested negative for COVID-19 (risk difference, 3.9%).
Previous retrospective studies of severe outcomes in children and adolescents with COVID-19 have yielded varying results, in part because of the variation in study populations, the researchers noted in their discussion of the findings. “Our study population provides a risk estimate for youths brought for ED care.” Therefore, “Our lower estimate of severe disease likely reflects our stringent definition, which required the occurrence of complications or specific invasive interventions,” they said.
The study limitations included the potential overestimation of the risk of severe outcomes because patients were recruited in the ED, the researchers noted. Other limitations included variation in regional case definitions, screening criteria, and testing capacity among different sites and time periods. “Thus, 5% of our SARS-CoV-2–positive participants were asymptomatic – most of whom were tested as they were positive contacts of known cases or as part of routine screening procedures,” they said. The findings also are not generalizable to all community EDs and did not account for variants, they added.
However, the results were strengthened by the ability to compare outcomes for children with positive tests to similar children with negative tests, and add to the literature showing an increased risk of severe outcomes for those hospitalized with positive tests, the researchers concluded.