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Could young kids spread COVID-19 as much as older children/adults; what does research say?

M3 India Newsdesk Aug 11, 2020

Researchers have recently discovered that children younger than 5 years with mild to moderate COVID-19 have much higher levels of genetic material for the virus in the nose compared to older children and adults. In a paper published in JAMA Pediatrics online on July 30, 2020, the researchers showed the possibility that the youngest children transmit the virus as much as other age groups.

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The lead author Dr.Taylor Heald-Sargent, pediatric infectious diseases specialist at Lurie Children's and Assistant Professor of Pediatrics at Northwestern University Feinberg School of Medicine said that they found that children under 5 with COVID-19 have a higher viral load than older children and adults, which may suggest greater transmission, as we see with respiratory syncytial virus, also known as RSV.

"This has important public health implications, especially during discussions on the safety of reopening schools and day-care." he cautioned.

"Our study was not designed to prove that younger children spread COVID-19 as much as adults, but it is a possibility," says Dr. Heald-Sargent. "We need to take that into account in efforts to reduce transmission as we continue to learn more about this virus."

Children may get infected with SARS-CoV-2; however, they generally suffer from only mild symptoms when compared to adults. We know that children spread respiratory and gastrointestinal infections in the population. However, data on SARS-CoV-2 spread is very sparse. In the early reports, researchers did not find strong evidence that children spread the disease. Since classes closed early as a part of the pandemic response, they could not investigate schools as a source of community transmission. The researchers’ recent finding is that replication of the virus in older children leads to similar levels of viral nucleic acid as adults but in significantly higher levels in children younger than five years.

Study details

From March 23 to April 27, 2020, the researchers carried out SARS-CoV-2 reverse transcription polymerase chain reaction on nasopharyngeal swabs collected at various inpatient, outpatient, emergency department and drive through testing sites in Chicago, Illinois. The team fulfilled the legal requirements for the study.

The researchers collected swabs and recorded PCR amplification cycle threshold (CT) values with lower values indicating higher viral load. The final group included 145 patients with mild to moderate illness with one week of the onset of symptoms. They compared three groups:

  • Patients younger than 5 years (n=46)
  • Older children aged 5 to 17 years (n=51)
  • Adults aged 17 to 65 years (n=48)


Researchers found similar median values of 11.1 for CT for older children and adults. Young children had significantly lower median CT values of 6.5 indicating that young children have equivalent or more viral nucleic acid in their upper respiratory track compared to older children and adults. The observed CT values between young children and adults approximate a 10-fold to 100-fold greater concentration of viral load in the upper respiratory tracts of young children.

The researchers conceded that their study is limited to the detection of viral nucleic acid, rather than infectious virus. They stated that virus pediatric studies reported a correlation between higher nucleic acid levels and the ability to culture infectious virus.

Researchers have demonstrated with respiratory syncytial virus that children with high levels of viral load are more likely to transmit. The possibility that young children can be potential drivers to transmit SARS-CoV-2 in the general population is of great concern when public health authorities withdraw restrictions in schools.

For younger children, we may have to consider other mitigating factors. Younger children with lower lung volume may exhale less air. Even when they may have higher viral load the number of viruses released by them may be less. In addition, they exhale that air at lower heights. Some of them at ground level making it less likely those adults would breathe it in.

“Behavioural habits of young children and close quarters in school and daycare settings raise concerns for SARS-CoV-2 amplification in this population as public health restrictions are eased. In addition to public health implications, this population will be important for targeting immunisation efforts as SARS-CoV-2 vaccines become available,” the researchers concluded.

Different views

Based on a large study from South Korea published as an early release article in Emerging Infectious Diseases Journal of the Centers for Disease Control and Prevention, The New York Times (July 18, 2020) reported that children younger than 10 transmit to others much less often than adults do, but the risk is not zero. And those between the ages of 10 and 19 can spread the virus at least as well as adults do.

The JAMA Pediatrics study suggests a greater role for transmission by younger children. Either way, public health authorities have to consider these facts when they relax conditions imposed on schools when they open schools and when they organise immunisation efforts.

A commentary in Pediatrics Journal

A commentary published in the journal Pediatrics, the official, peer-reviewed journal of the American Academy of Pediatrics on July 10 this year concludes that, "Children infrequently transmit COVID-19 to each other or to adults and that many schools, provided they follow appropriate social distancing guidelines and take into account rates of transmission in their community, can and should reopen in the fall.”

The authors, Dr. Benjamin Lee, and Dr. William V. Raszka, both pediatric infectious disease specialists on the faculty of the University of Vermont's Larner College of Medicine based their conclusions on a new study published in the current issue of Pediatrics, 'COVID-19 in Children and the Dynamics of Infection in Families' and four other recent studies that examine COVID-19 transmission by and among children.

After reviewing the results of four studies, Dr. Raszka who is also an associate editor of Pediatrics stated that the data are striking.

“The key takeaway is that children are not driving the pandemic. After six months, we have a wealth of accumulating data showing that children are less likely to become infected and seem less infectious; it is congregating adults who aren't following safety protocols who are responsible for driving the upward curve."

"There is widespread transmission of COVID-19 in Texas today, with many adults congregating without observing social distancing or wearing masks," he said. "While we don't yet know the dynamics of the outbreak, it is unlikely that infants and children in daycare are driving the surge. Based on the evidence, it's more plausible that adults are passing the infection to the children in the vast majority of cases," he suggested.

Additional support for the notion that children are not significant vectors of the disease comes from mathematical modeling, the authors say. Models show that community-wide social distancing and widespread adoption of facial cloth coverings are far better strategies for curtailing disease spread. The fact that schools have reopened in many Western European countries and in Japan without seeing a rise in community transmissions bears out the accuracy of the modeling,” a press release from the University of Vermont asserted.


Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

Dr. K S Parthasarathy is a freelance science journalist and a former Secretary of the Atomic Energy Regulatory Board. He is available at ksparth@yahoo.co.uk

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