Asymptomatic SARS-CoV-2 Infections in Kids Tied to Local Rates

Jake Remaly

August 27, 2020

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As communities wrestle with the decision to send children back to school or opt for distance learning, a key question is how many children are likely to have asymptomatic SARS-CoV-2 infections. Researchers have now found that the prevalence of asymptomatic infections in children correlates with the overall incidence of COVID-19 in the local population, according to an analysis of data from 28 US children's hospitals.

"The strong association between prevalence of SARS-CoV-2 in children who are asymptomatic and contemporaneous weekly incidence of COVID-19 in the general population...provides a simple means for institutions to estimate local pediatric asymptomatic prevalence from the publicly available Johns Hopkins University database," researchers say in an article published online August 25 in JAMA Pediatrics.

Ana Marija Sola, BS, a researcher at the University of California, San Francisco, School of Medicine, and colleagues examined the prevalence of SARS-CoV-2 infection among 33,041 children who underwent routine testing in April and May when hospitals resumed elective medical and surgical care. The hospitals performed reverse transcription–polymerase chain reaction tests for SARS-CoV-2 RNA before surgery, clinic visits, or hospital admissions. Pediatric otolaryngologists reported the prevalence data through May 29 as part of a quality improvement project.

In all, 250 patients tested positive for the virus, for an overall prevalence of 0.65%. Across 25 geographic areas, the prevalence ranged from 0% to 2.2%. By region, prevalence was highest in the Northeast, at 0.90%, and the Midwest, at 0.87%; prevalence was lower in the West, at 0.59%, and the South, at 0.52%.

To get a sense of how those rates compared with overall rates in the same geographic areas, the researchers used the Johns Hopkins University confirmed cases database to calculate the average weekly incidence of COVID-19 for the entire population for each geographic area.

"Asymptomatic pediatric prevalence was significantly associated with weekly incidence of COVID-19 in the general population during the 6-week period over which most testing of individuals without symptoms occurred," Sola and colleagues report. An analysis using additional data from 11 geographic areas demonstrated that this association persisted at a later time point.

The study provides "another window on the question of how likely is it that an asymptomatic child will be carrying coronavirus," said Susan E. Coffin, MD, MPH, an attending physician for the Division of Infectious Diseases at Children's Hospital of Philadelphia. However, important related questions remain, said Coffin, who was not involved with the study.

For one, it is unclear how many children remain asymptomatic in comparison with those who were in a presymptomatic phase at the time of testing. And importantly, "[w]hat proportion of these children are infectious?" said Coffin. "There is some data to suggest that children with asymptomatic infection may be less infectious than children with symptomatic infection."

It also could be that patients seen at children's hospitals differ from the general pediatric population. "What does this look like if you do the exact same study in a group of randomly selected children, not children who are queueing up to have a procedure?.... And what do these numbers look like now that stay-at-home orders have been lifted?," Coffin asked.

Further studies are needed to establish that detection of COVID-19 in the general population is predictive of the prevalence of SARS-CoV-2 infection in asymptomatic children, Coffin said.

The authors have disclosed no relevant financial relationships.

JAMA Pediatr. Published online August 25, 2020. Full text

Jacob Remaly is a staff journalist at Medscape Medical News and MDedge. He has covered healthcare and medicine for more than 5 years. He can be reached at

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