The coronavirus has been affecting our lives for the past few months and many students are eager to return to school. As the upcoming school year approaches and public schools/daycares open up, it's important to understand the transmission potential of the coronavirus in children. Previous research (See Are Schools Ready to Reopen) has shown that children are a not major contributor of COVID-19 and generally present mild to no symptoms compared to adults. However, a study published on July 30, 2020 in JAMA (Journal of the American Medical Association) Pediatrics suggests that children may be greater carriers of the coronavirus than we may expect.
The Study and Results
In this study, one hundred and forty five individuals, aged younger than 1 month to 65 years with mild to moderate illness (within 1 week of initial symptoms), were tested for evidence of the virus' RNA. These were all patients of a hospital located in Chicago, Illinois. The participants were broken down and compared in 3 age groups: 46 young children aged less than 5 years, 51 older children aged 5-17 years and 48 adults aged 18-65 years. Nasal swabs were collected from the patients with a question in mind- do different age groups with comparable COVID-19 severity all carry similar viral loads?
A cycle threshold (CT) value which is measured using a polymerase chain reaction (PCR) machine, indicates the viral load in each patient. CT values are inversely proportional to viral load; lower CT values indicate higher amounts of viral nucleic acid. Older children had similar median viral loads (CT value 11.1) compared to that of adults (CT value 11.0). However, younger children had significantly higher amounts of viral nucleic acid in their upper respiratory tract than older children or adults (CT value 6.5). Researchers estimate that younger children carry between 10 times and 100 times more coronavirus than older children or adults do.
Similar Studies
The results from this study are in line with similar studies from other countries. In Germany, children aged 1-11 years were found to have high viral loads compared to adults. A study from France showed that CT values of asymptomatic children were similar to that of children with obvious symptoms. This supports the idea that children can still carry high levels of virus without displaying any symptoms or signs of illness.
Conclusion
The analysis and results from this study suggest that children younger than 5 years with mild to moderate COVID-19, have high levels of SARS-CoV-2 viral RNA in their upper respiratory tract compared to older children (Ages 5-17) and adults. The study detects viral nucleic acid, as opposed to infectious nucleic acid, so the results cannot speak to children's ability to transmit the coronavirus to others. However, COVID-19 pediatric studies have reported a correlation between high nucleic acid levels and the ability to culture or maintain infectious viruses. Therefore, it's quite possible children are significant drivers of the spread of COVID-19, as results indicate that children with higher viral loads are more likely to transmit disease. Children could be infected with the coronavirus and carry high viral loads but show no symptoms. This is why it's imperative that everyone where's a mask outside, including children/adolescents, even if you don't think you are infected with COVID-19.
Sources
1. Taylor Heald-Sargent, MD. “Age-Related Differences in Nasopharyngeal SARS-CoV-2 Levels in Patients With Mild to Moderate COVID-19.” JAMA Pediatrics, 30 July 2020, jamanetwork.com/journals/jamapediatrics/fullarticle/2768952.
2. Heidt, Amanda. “Children Often Carry More Coronavirus than Adults Do: Study.” The Scientist Magazine®, www.the-scientist.com/news-opinion/children-often-carry-more-coronavirus-than-adults-study-67785.
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