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Frequency of Children vs Adults Carrying Severe Acute Respiratory Syndrome Coronavirus 2 Asymptomatically

Our take —

This retrospective cohort study among child and adult inpatients at a hospital in Milan, Italy reports a higher proportion of asymptomatic infections in adults compared to children. The findings suggest that children are less likely to be asymptomatically infected, however the limited sample size, older age of adults (median 77 years), and single facility setting, provide insufficient evidence to conclude that children are at a higher risk of carrying SARS-CoV-2 asymptomatically than adults.

Study design

Retrospective cohort

Study population and setting

The study included patients requiring hospitalization for noninfectious conditions after accessing the emergency department at the Fondazione Ca’ Granda Ospedale Maggiore Policlinico in Milan, Italy from March 1 to April 30, 2020. Subjects must have had two nasopharyngeal swabs and no symptoms nor history of COVID-19, nor known close contact with COVID-19 cases. 83 children (34 girls and 49 boys; median age, 5.3 [1.1-11.0] years) were included as well as 131 adults (51 women and 80 men; median age, 77 [57-84] years). The study retrospectively recorded data on age, sex, reason for admission, and development of any SARS-CoV-2 signs of infection within 48 hours of admission. A comparison of proportions between the pediatric and adult cohorts was made with the 2-tailed Fisher test.

Summary of Main Findings

Asymptomatic children were found to have evidence of SARS-CoV-2 infection be less frequently than asymptomatic adults (1 in 83 children [1.2%] vs 12 in 131 adults [9.2%]; p 0.02), with an odds ratio of 0.12 (95% CI, 0.02-0.95) compared with adults. None of the subjects developed signs or symptoms of SARS-CoV-2 infection in the 48 hours following admission. The study does not support the hypothesis that children are at higher risk of carrying SARS-CoV-2 asymptomatically than adults, and suggests reconsidering their role as facilitators of the spreading of SARS-CoV-2 infection.

Study Strengths

The retrospective design ensures complete data on all subjects and enables rapid turnaround of results. The simple study design facilitates repetition at other locations.


The study had a limited sample size, only included cases requiring hospitalization, and only included a single medical facility. The testing protocol was not specified (particularly, cycles of PCR) which affects comparability. The older age of adult study participants also limits comparability and fails to capture the asymptomatic prevalence of young and middle-aged adults. A community-based study would yield stronger conclusions.

Value added

This study adds to the limited data available on SARS-CoV-2 among children and counters the hypothesis that children are at higher risk of carrying SARS-CoV-2 asymptomatically than adults.

This review was posted on: 13 November 2020