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Infectious Diseases

Updated 03 September 2020

Why primary school kids infected with the Covid-19 virus may be hard to spot, according to a study

Children’s role in the spread of SARS-CoV-2 is becoming clearer, and evidence suggests that screening systems in schools should focus on age-related differences in symptoms.

  • Studies on children and SARS-CoV-2 show that kids play a significant role in virus transmission
  • A new study sheds further light on this, indicating that infected children could be hard to spot
  • Screening processes and the implementation of non-pharmaceutical interventions in schools settings are therefore critical 

Scientists have been trying to make sense of data on the role children play in the transmission of SARS-CoV-2, the virus that causes Covid-19, since the start of the pandemic.

A growing body of evidence suggests that children may play a larger role in transmission than previously thought.

To add to this evidence, a recent study by scientists at Duke University School of Medicine found that infected primary school children could be hard to spot.

Based on their findings, the researchers recommend screening strategies that are in place in schools and daycare centre should focus on age-related differences in symptoms.

The study was published in preprint server medRxiv and has not yet been peer-reviewed.

Virus transmission happening from child to child

For their study, the team looked at 382 children and young adults under the age of 21 who had come into close contact with a person infected with the virus.

Of the 382 children, 293 (77%) tested positive for SARS-CoV-2 either before or during the study.

The researchers reported the following results:

  • In the 6–13 age group, only 61% of infected participants displayed symptoms.
  • In infected children under the age of 6, 75% were symptomatic.
  • In those above the age of 13, 76% were found to display symptoms of infection.

The researchers also wrote that nearly one-third of infected children with an infected sibling did not have close contact with an infected adult, suggesting that the virus was transmitted from child to child.

“Age-related differences in the clinical manifestations of SARS-CoV-2 infection must be considered when evaluating children for Covid-19 and in developing screening strategies for schools and childcare settings,” they wrote.

What another recent study says

Health24 recently reported on a comprehensive study published earlier this month that suggests that children are “silent spreaders” of the virus.

The paper, which was published in the Journal of Pediatrics, showed that among the study participants (paediatric patients between the ages of 0–22) who tested positive for SARS-CoV-2, a significantly higher level of virus was detected, compared to hospitalised adults in ICUs (intensive care units) for Covid-19 treatment.

"I was not expecting the viral load to be so high. You think of a hospital, and of all of the precautions taken to treat severely ill adults, but the viral loads of these hospitalised patients are significantly lower than a 'healthy child' who is walking around with a high SARS-CoV-2 viral load,”  said Lael Yonker, MD, director of the MGH Cystic Fibrosis Center and lead author of the study.

Senior author of the paper, Alessio Fasano, MD, director of the Mucosal Immunology and Biology Research Center at MGH also commented that their results show that children are not protected against this virus, and that “we should not discount children as potential spreaders for this virus".

Since schools around the world are slowly reopening, the researchers encouraged a safe return-to-school policy that includes not only relying on body temperature or symptom monitoring to identify infection cases in the school setting, but non-pharmaceutical interventions (NPIs) such as  physical distancing, face mask-wearing, hand hygiene, and remote and in-person screening, among others.