Children play an unexpected role in COVID-19 transmission

Researchers at Massachusetts General Hospital (MGH) have conducted the most comprehensive study of COVID-19 pediatric patients to date. The study reveals that children play a much larger role in the spread of COVID-19 than what was previously expected.

The investigation was focused on 192 children from infants to age 22. Among these subjects, 49 tested positive for SARS-CoV-2 and 18 tested positive for a late-onset illness related to COVID-19.

Compared to hospitalized adults being treated for COVID-19 in the ICU, the infected children were found to have significantly higher levels of the virus in their airways.

“I was surprised by the high levels of virus we found in children of all ages, especially in the first two days of infection,” said study lead author Dr. Lael Yonker. 

“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 hospitalized patients are significantly lower than a ‘healthy child’ who is walking around with a high SARS-CoV-2 viral load.”

The risk of contagion is much greater with a higher viral load. Furthermore, some of the typical COVID-19 symptoms – runny nose, fever, and cough – can be easily overlooked because they often overlap with other illnesses such as the flu or the common cold.

The researchers compared the expression of the viral receptor and antibody response in healthy children, those with acute SARS-CoV-2 infection, and a few children with Multisystem Inflammatory Syndrome in Children (MIS-C).

The results of the analysis, which was based on nose and throat swabs and blood samples, have major implications for the reopening of schools and daycares.

“Kids are not immune from this infection, and their symptoms don’t correlate with exposure and infection,” said study senior author Dr. Alessio Fasano.

“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.”

“However, our results show that kids are not protected against this virus. We should not discount children as potential spreaders for this virus.”

The experts noted that even though children with COVID-19 are not as likely to become as severely ill, they can spread infection and bring the virus into their homes as asymptomatic carriers while attending school. 

The study findings also suggest that younger children may have lower numbers of the virus receptor than older children and adults. However, regardless of having a lower susceptibility to developing COVID-19 infection, they still carry a high viral load.

The researchers studied immune response in MIS-C, which is a multi-organ infection that can develop in children with COVID-19 several weeks after infection. The doctors found that complications from the accelerated immune response seen in MIS-C can include severe cardiac problems, shock, and acute heart failure. 

“This is a severe complication as a result of the immune response to COVID-19 infection, and the number of these patients is growing,” said Dr. Fasano. “And, as in adults with these very serious systemic complications, the heart seems to be the favorite organ targeted by post-COVID-19 immune response.”

According to the experts, understanding MIS-C and post-infectious immune responses from pediatric COVID-19 patients is critical for developing next steps in treatment and prevention strategies. 

When it comes to children returning to school, Dr. Fasano and Dr. Yonker said that SARS-CoV-2 infection cannot be identified based on body temperature or symptom monitoring alone. They recommend that routine screening of all students for SARS-CoV-2 infection with timely reporting of the results should be prioritized in return-to-school policies.

“This study provides much-needed facts for policymakers to make the best decisions possible for schools, daycare centers and other institutions that serve children,” said Dr. Fasano. “Kids are a possible source of spreading this virus, and this should be taken into account in the planning stages for reopening schools.”

Dr. Fasano fears that a rushed return to school without proper planning could result in a spike in cases of COVID-19 infections. “If schools were to reopen fully without necessary precautions, it is likely that children will play a larger role in this pandemic,” concluded the study authors.

The research is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer