As the coronavirus disease (COVID-19) continues to wreak havoc across the globe, it has been thought that children mostly seemed to be spared by severe illness. In the majority of cases, children infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) only develop a mild illness, with some tagged as asymptomatic.
Now, new evidence shows that children carry high levels of the SARS-CoV-2 virus even without falling ill, which may impact the spread of the virus to others, especially those who are at high risk of developing severe COVID-19.
The team also found that infected children younger than 5 years old may carry up to 100 times as much of SARS-CoV-2 in their noses and throats as adults.
Colorized scanning electron micrograph of a cell (green) infected with SARS-CoV-2 virus particles (purple), isolated from a patient sample. Image captured at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID
Higher levels of viral genetic material
The study, published in the journal JAMA Pediatrics, suggests the possibility that the youngest children transmit the virus as much as other groups, even if they only develop mild to moderate illness.
The study may highlight the ability of younger children to spread the virus to others, which could help revise current guidelines in containing the spread of the virus.
Children are susceptible to infection with SARS-CoV-2 but generally present with only mild symptoms compared to adults. Earlier reports did not find strong evidence of children as key drivers in the spread of SARS-CoV-2. However, school closures early in pandemic responses prevented large-scale investigations for schools as a source of community transmission.
To arrive at their findings, the research team from the Ann & Robert H. Lurie Children's Hospital, Chicago, and Northwestern University Feinberg School of Medicine, Chicago, looked at swab samples from 95 children, a majority of whom reported cough or a low-grade fever in Chicago.
The team found that children under 5 with COVID-19 have higher levels of viral load than older children and adults, suggesting a risk of higher transmission, as seen in the respiratory syncytial virus, also called RSV. The team believes that the study findings are significant, especially during discussions on the safety of reopening schools and daycare.
"The observed differences in median CT values between young children and adults approximate a 10-fold to 100-fold greater amount of SARS-CoV-2 in the upper respiratory tract of young children," the researchers explained.
They added that the study is limited to the detection of viral nucleic acid, rather than an infectious virus. Also, studies in children about COVID-19 shows a correlation between higher nucleic acid levels and the ability to culture infectious virus.
One limitation of the study was, it was conducted at the time when lockdown measures were in place, and schools are closed. Hence, they had fewer opportunities to transmit. Further studies are needed to look at the transmissibility of SARS-CoV-2 in children.
"Our study was not designed to prove that younger children spread COVID-19 as much as adults, but it is a possibility. We need to take that into account in efforts to reduce transmission as we continue to learn more about this virus," Dr. Taylor Heald-Sargent, a pediatric infectious diseases specialist at Lurie Children's Hospital of Chicago," said.
The study may help shape current guidelines amid the coronavirus pandemic, adding children as key drivers of SARS-CoV-2 spread in the general population. Also, younger children have behavioral habits that may increase the risk of transmission, such as playing with other kids in school. Also, close quarters in school and daycare settings raise concern for the spread of SARS-CoV-2.
The new information on how these children can transmit the virus may affect school opening in a few months. In addition to public health implications, children are essential for targeting vaccine efforts when they become available.
COVID-19 global toll
The global case toll tied to COVID-19 has topped 17.53 million, with more than 678,000 people who died due to the infection. The United States remains the nation hardest hit, surpassing 4.56 million cases and over 153,000 deaths, while Brazil has more than 2.66 million people, with over 92,000 deaths.
Heald-Sargent, T., Muller, Q., Zheng, et al. (2020). Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19). JAMA Pediatrics. https://jamanetwork.com/journals/jamapediatrics/fullarticle/2768952
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