Researchers at Massachusetts General Hospital (MGH) and Mass General Hospital for Children (MGHfC) have recently conducted a study on 192 pediatric patients aged 0-22 years (49 children tested positive for Covid-19 and another 18 had a late onset Covid-19 related disease). The results of this study explain that children could play a more important role in the spread of the virus than previously thought, as they show a significantly higher level of virus in their respiratory tract than adults.

Lael Yonker, director of the MGH Cystic Fibrosis Center, and author of the study, said: “the viral load of the hospitalized adults patients are significantly lower than that of healthy children walking around with a high Sars-CoV-2 viral load.” (Viral load refers to the amount of virus in a person’s blood).

Researchers have also 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” (a systemic infection that can develop in children due to the Covid-19 even several weeks after the contagion). Complications of the accelerated immune response in MIS-C cases may also include severe heart problems, shock and acute heart failure. This is a serious complication due to the immune response to Covid-19 infection. The data show that the number of children with MIS-C due to the Corona virus is increasing dramatically.

Alessio Fasano, director of the research center of immunology and mucosal biology of the MGH and senior author of the study, said that: “During this Covid-19 pandemic, symptomatic subjects were examined primarily, so the erroneous conclusion was reached that the vast majority of those infected are adults. However, our results show that children are not protected from this virus and should also be considered as potential infectious”.

In essence, the MGH researchers agree that it would be ineffective to rely only on symptom or temperature monitoring when schools reopen. They stress the importance of infection control measures, including strict compliance with social distance, universal use of the mask (when it can be implemented), effective hand washing protocols and a combination of distance and classroom learning. For a safe return to school they recommend routine and continuous screening of all students for Sars-CoV-2 infection with timely reporting of results.

The outcome of the US study have been contested by many experts in the field, including: Dr. Simon Clarke, Associate Professor of cellular microbiology at the University of Reading and Adilia Warris, Professor of pediatric infectious diseases at the University of Exeter.

Dr Clarke argues that it had been known for some time that children contract the virus and produce it in large quantities; however, it is less clear how children can spread the virus or how their age can affect this. He also pointed out that the study of the MGH increases our understanding of the extent of infection in children, but it does not make it absolutely clear how Covid-19 is spread among children; that’s because the research only considered symptomatic children and did not measure the transmission of the virus itself.

Professor Warris claims that: “the American study was not designed to assess the risk of transmission and although a high viral load contributes to the level of contagiousness, it is not the only factor that plays a role”. According to Warris, the study was only conducted on children who were already hospitalized and not on “healthy” children who were quietly walking around the street, so the evidence gathered by the MGH team would not be sufficient to broadly analyze the situation.

Warris also points out that: the authors of the study demonstrate that children with respiratory problems, who were tested positive for Sars-CoV-2, showed viral loads comparable to adult hospitalized patients, especially in the first two days of symptoms. Warris states that analyzing this study in detail It is interesting, however, to know that: among the children who had such symptoms, only about 28% were positive, and of these, more than 60% were over 11 years old, 26% were obese (with less than 10% in the non-Sars-CoV-2 group), and exposure to the virus was from Mom or Dad (77%). So, basically, according to the professor the largest role in virus transmission is always played by adults.