The study raises new questions about viral load in asymptomatic children with COVID-19

Review by Emily Henderson, Bachelor of ScienceOctober 22, 2020

As a study published in, new questions are at the forefront. Journal of Clinical Microbiology Nine children’s hospitals found that most asymptomatic children who tested positive for COVID-19 had relatively low levels of the virus compared to symptomatic children. The authors warn that the reason for this discovery is unknown and that more questions need to be answered.

Were asymptomatic children generally tested late in the illness, and were their viral loads potentially higher near the onset of their infection? Do asymptomatic children have as high viral load as symptomatic children when tested early in the disease? Or do asymptomatic children usually carry as much virus as symptomatic children? If so, how does reduced viral load affect the risk of infection? These questions are essential to further clarify the public health effects of pediatric COVID-19.

These findings provide some reassurance about the safety of asymptomatic infected children attending school, but these unanswered questions are to reduce the prevalence of COVID-19 in day care, It suggests that risk mitigation measures in schools and communities remain important. Children must continue to wear masks, stay socially distant, and wash their hands frequently. At this stage, it is not possible to predict which children are more or less likely to have the virus. This is because there were higher asymptomatic children in all age groups tested. Viral load.. However, even the group of asymptomatic children with the highest viral load in our study had lower viral load than the symptomatic children. “

Larry Kociolek, MD, Lead Author, Pediatric Infectious Diseases Specialist at Anne & Robert H. Lully Children’s Hospital in Chicago, Associate Professor of Pediatrics, Northwestern University School of Medicine, Fineberg

The study included 339 asymptomatic children and 478 symptomatic children (ages 0-17) with matching age groups. All children in this study were screened for COVID-19 positive using PCR tests at nine children’s hospitals in the United States and Canada. The team centered on institutional median Ct values ​​from symptomatic children tested in that assay so that PCR data from different assays used in the nine centers could be combined. The cycle threshold (Ct) value was adjusted and converted to an estimate as viral load (copy / mL). This is the first large-scale, comprehensive study of SARS-CoV-2 viral load in asymptomatic children.

The analysis showed that asymptomatic children with recent contact with diabetes and / or COVID-19 cases, and children tested for surveillance purposes (rather than preprocedural or pre-hospital purposes), had the highest viral load. Quartile. The authors found that patients with a high likelihood of recent infection (contact / surveillance) were likely to have high viral load, and the timing of infection compared to diagnostic tests was found in asymptomatic children in the study. It states that it suggests that it affected the viral load. However, they also note that even in the asymptomatic surveillance subcohort with the highest viral load, the median viral load was significantly lower than in the symptomatic cohort.

“We need to know the peak viral load in asymptomatic children with COVID-19,” said Dr. Nilapolok, MD and associate professor at the Boston Children’s Hospital Institute for Infectious Disease Diagnosis. I will. Of Pathology and Medicine at Harvard Medical School. “In this study, the timing of the test only missed the peak in many asymptomatic children, or the asymptomatic children had lower viral load peaks than the actual symptomatic children. Is not it?”

The authors also point out that the levels of the virus found in asymptomatic children were much lower than those detected by the rapid antigen tests available.

“Rapid antigen testing is less sensitive than PCR testing used in hospitals, and many asymptomatic children in our study are negative using rapid testing based on an understanding of detection limits. It’s important to recognize that it was likely to have happened. Those tests, “said Dr. Pollock. “Our findings should call attention to the use of low-sensitivity tests in asymptomatic screening programs in pediatric populations. Overall, viral load in asymptomatic children, especially in the early stages of infection. I would like to encourage more research to better understand the peak viral load. “