A study of pediatric COVID-19 patients finds that children have a higher viral load than hospitalized adults and may contribute to the spread of COVID-19 more than previously thought.

A photo of elementary aged children wearing masks in a classroom to accompany the article, "COVID-19: children have a higher viral load than adults."Share on Pinterest
Research indicates that children may transmit COVID-19 at a higher rate than previously thought.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

As schools in the United States plan for reopening — with some opening already — some people have growing concerns surrounding children’s ability to spread COVID-19.

Parents have voiced concerns that children may pass on the disease to more vulnerable members of the household, while in some states, teachers have protested the re-openings on the basis of safety.

Instances of schools closing soon after re-opening due to reports of positive COVID-19, and a recent report from the American Academy of Pediatrics describing some 339,000 cases of COVID-19 among children in the U.S., has fuelled these concerns. 

This latest evidence contradicts earlier statements made by some governments and public health officials that children are at low risk from COVID-19.

To help clarify the situation, a team from Massachusets General Hospital in Boston has assessed the nature of the disease in children, evaluating viral burden, susceptibility to disease, and immune response in 192 patients seen at the hospital.

The study is the most comprehensive research of COVID-19 pediatric patients to date, and it appears in the Journal of Pediatrics.

Stay informed with live updates on the current COVID-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.

High viral load

The study involved 192 people from babies to people 22 years of age, with an average age of 10. Of these, roughly a quarter had received a confirmed SARS-CoV-2 diagnosis.

Tests from airway samples showed that pediatric patients had a significantly higher viral load than hospitalized adults with severe COVID-19.

This is important because the risk of passing SARS-CoV-2 on to somebody else is greater with a higher viral load.

“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,” says Dr. Lael Yonker, lead author of the study.

Also, of the children with confirmed COVID-19, only half presented with fever, suggesting that doctors may miss some diagnoses in younger patients.

“Kids are not immune from this infection,” says Dr. Alessio Fasano, senior author of the study. “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.” 

Based on these new findings, Dr. Fasano says that doctors and other experts should not discount children as potential spreaders of the new coronavirus, despite some previous contrary evidence.

Inflammatory syndrome

Although the research suggests that children, in general, have fewer ACE2s — receptors that the new coronavirus uses to infect healthy cells — it also found no associations between being younger and having a lower viral load.

This suggests that children can transmit the virus, regardless of their susceptibility to developing COVID-19. This finding is particularly important for multi-generational households, where vulnerable older adults live together with children, or indeed, any household with a vulnerable member.

As well as those with diagnosed COVID-19, 18 children in the study (almost 10% of the sample) developed Multisystem Inflammatory Syndrome in Children (MIS-C). This potentially dangerous inflammatory condition can develop weeks after contracting SARS-CoV-2.

Complications from MIS-C can include severe cardiac problems. “This is a severe complication as a result of the immune response to COVID-19 infection, and the number of these patients is growing,” says Dr. Fasano.

What does this mean for schools?

The researchers conclude that children could play a more significant role in the spread of COVID-19 than previously thought and make several recommendations regarding the opening of schools.

“Kids are a possible source of spreading this virus, and this should be taken into account in the planning stages for reopening schools.” 

– Dr. Alessio Fasano, senior author

They say doctors should not use symptoms and body temperature to check for infection, as many children in the study did not have a fever, and a person can carry SARS-CoV-2 without having any symptoms.

Instead, the researchers recommend robust infection control measures, including social distancing, mask-wearing where possible, regular hand-washing, and remote learning.

Most importantly, they say the routine testing of students for SARS-CoV-2 infection is a key element of a safe return-to-school policy.

“If schools were to reopen fully without necessary precautions, it is likely that children will play a larger role in this pandemic,” the authors conclude.

For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.