New York: While most studies have stressed that children are not the harbingers of Covid-19, a comprehensive study now claims that children play a larger role in the community spread of the novel coronavirus than previously thought.
In a study of 192 children aged 0-22, published in the Journal of Pediatrics, 49 children tested positive for SARS-CoV-2, and an additional 18 children had late onset, Covid-19-related illness.
The infected children were shown to have a significantly higher level of virus in their airways than adults hospitalised in ICUs for Covid-19 treatment.
"I was surprised by the high levels of virus we found in children of all ages, especially in the first two days of infection. I was not expecting the viral load to be so high," said study author Lael Yonker from the Massachusetts General Hospital (MGH) in the US.
"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," Yonker added.
According to the researchers, transmissibility or risk of contagion is greater with a high viral load.
And even when children exhibit symptoms typical of Covid-19, like fever, runny nose and cough, they often overlap with common childhood illnesses, including influenza and the common cold.
Along with the viral load, the team examined the expression of the viral receptor and antibody response in healthy children, children with acute SARS-CoV-2 infection and a smaller number of children with Multisystem Inflammatory Syndrome in Children (MIS-C).
The researchers noted that although children with Covid-19 are not as likely to become as seriously ill as adults, as asymptomatic carriers or carriers with few symptoms attending school, they can spread infection and bring the virus into their homes.
This is a particular concern for families in certain socio-economic groups, which have been harder hit in the pandemic, and multi-generational families with vulnerable older adults in the same household.
In the Mass General Hospital for Children (MGHfC) study, 51 per cent of children with acute SARS-CoV-2 infection came from low-income communities compared to two per cent from high-income communities.
In another breakthrough finding from the study, the researchers challenge the current hypothesis that because children have lower numbers of immune receptors for SARS-CoV-2, this makes them less likely to become infected or seriously ill.
Data from the group show that although younger children have lower numbers of the virus receptor than older children and adults, this does not correlate with a decreased viral load.
According to the authors, this finding suggests that children can carry a high viral load, meaning they are more contagious, regardless of their susceptibility to developing Covid-19 infection.
"During this Covid-19 pandemic, we have mainly screened symptomatic subjects, so we have reached the erroneous conclusion that the vast majority of people infected are adults," said study author Alessio Fasano from MGH.
"However, our results show that kids are not protected against this virus. We should not discount children as potential spreaders for this virus," Fasano noted.
Recently, a study, published in the journal JAMA Pediatrics, discovered that children younger than five years with mild to moderate Covid-19 can spread coronavirus as much as older children and adults.
Another study published last month in the journal 'American Journal of Physiology' revealed that children are more often spared from severe illness associated with Covid-19 than adults.