Most kids infected with COVID-19 who don't have symptoms have low levels of the virus, compared with symptomatic children, a new study finds.
Researchers said it's not clear why.
"While these findings provide some reassurance about the safety of asymptomatically infected children attending school, these unanswered questions suggest that risk mitigation measures in day cares, schools and the community remain critical to reduce the spread of COVID-19," said study first author Dr. Larry Kociolek, a pediatric infectious diseases expert at Ann and Robert H. Lurie Children's Hospital in Chicago.
"Children must continue to wear masks, maintain social distance and wash their hands frequently," he said in a hospital news release.
Right now, it's impossible to predict which kids are likely to carry more or less virus, because in every age group researchers tested, some asymptomatic kids had a higher viral load, Kociolek said.
"However, even the groups of asymptomatic kids with highest viral load in our study still had lower viral loads than the children with symptoms," he noted.
The study included 339 asymptomatic and 478 symptomatic children who tested positive for COVID-19.
Researchers found that asymptomatic kids with diabetes or recent contact with a COVID-19 patient, and those tested for surveillance purposes (rather than pre-procedure purposes) were more likely to be among those with the highest levels of virus.
"We now need to know what the peak viral loads are in asymptomatic kids with COVID-19," said principal investigator Dr. Nira Pollock, associate medical director of the Infectious Diseases Diagnostic Laboratory at Boston Children's Hospital. "Did the timing of testing just miss the peak in many of the asymptomatic kids in this study, or do asymptomatic kids actually have lower peak viral loads than symptomatic kids?"
Researchers did find that viral levels in asymptomatic children were lower than those detectable by rapid antigen tests.
"It is important to recognize that rapid antigen tests are less sensitive than the PCR tests used in hospitals and that many of the asymptomatic kids in our study likely would have tested negative using the rapid tests based on our understanding of the limits of detection of those tests," Pollock said in the release.
She said the findings add to cautions about using low-sensitivity tests for asymptomatic screening of children.
"Overall, we want to encourage more studies to better understand the viral loads in asymptomatic kids -- particularly peak viral loads early in infection," Pollock added.
The findings were recently published in the Journal of Clinical Microbiology.More information
For more on COVID-19, see the U.S. Centers for Disease Control and Prevention.
-- Steven Reinberg
SOURCE: Lurie Children's Hospital, news release, Oct. 22, 2020
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