The World Health Organization and UNICEF have issued new age-specific mask guidance for children, recommending looser masking protocols for younger children.

The agency’s new guidance comes the week after a new study from researchers at the Massachusetts General Hospital found that children infected with COVID-19 had higher virus levels in their nose and throats than adults, despite showing less severe or no symptoms. The findings suggest that children may be “silent spreaders” of the virus, expelling more virus than infected adults despite being less prone to getting symptoms of COVID-19 themselves.

“[Based on preliminary studies] there appears to be a difference in transmission by age group, with the younger children able to transmit less than teenagers, for example, but this data is really limited,” Maria Van Kerkhove, WHO technical lead for COVID-19, told reporters Friday.

Children under the age of 5 should not be required to wear masks, according to the new guidance.

The guidance takes a “risk-based” approach to recommendations for kids between the ages of 6 to 11 years old. They should wear masks if they have adequate adult supervision, they’re able to safely don and doff a mask themselves, or they reside in areas of high COVID-19 transmission. Those 6 to 11 years old should also wear masks if they are interacting with people who have a higher risk of developing severe COVID-19 disease, such as people over the age of 65 or those with preexisting conditions.

Children older than 12 should wear fabric masks under the same conditions as adults – in areas of high transmission, where maintaining physical distancing is impossible, or confined and crowded environments.

“What we understand about transmission in children is still limited,”  Van Kerkhove admitted.

But with the upcoming fall semester beginning all over the world, understanding the role of children in COVID-19 transmission is even more urgent as countries grapple with the decision to reopen classrooms, or pursue remote learning.

While the risk of severe disease in children is low, public health officials are concerned that children who get infected at school could bring the virus home, potentially exposing older family members or those with preexisting conditions.

Ultimately, the success of controlling the spread of the virus in schools is dependent on controlling the virus’ transmission in the larger community.

“Schools do not operate in isolation. They operate in communities and… if there’s widespread transmission in those communities or intense transmission is possible, the virus can enter the school system,” said Van Kerkhove.

“Just because kids or others have masks does not mean we can forget about the other measures,”  added WHO Health Emergencies Executive Director Mike Ryan. “Wearing a mask is not an alternative to physical distancing. It’s not an alternative to hand washing, and it’s not an alternative to decompressing classes.”

WHO’s current guidance for masking in classroom settings recommends that schools develop a policy on wearing masks or face coverings in line with national or local recommendations.

Children With Few Or No Coronavirus Symptoms May Carry More Virus Than Hospitalized Adults

In a study of 192 pediatric patients at Massachusetts General Hospital and Mass General Children’s Hospital, researchers found that infected children had significantly higher levels of virus in their airways than infected adults.

Levels of virus in the children’s noses and throats were highest in the first two days of symptoms – significantly higher than viral loads in hospitalized adult patients experiencing more severe symptoms.

“I was not expecting the viral load to be so high,” said lead author Lael Yonker in a press release. “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 higher the level of virus in the airways, the more likely it is for a patient to transmit the virus onwards. Coupled with the fact that children generally tend to have more mild COVID-19 disease, the study findings imply that children could be a major, unmeasured source of the virus’ spread.

“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,”  said Alessio Fassano, director of the Mucosal Immunology and Biology Research Center at MGH and senior author on the paper.

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

Out of the cohort of patients in Massachusetts, some 49 children tested positive for SARS-CoV-2, but only 25 had a fever. Many of the children presented with non-specific symptoms such as a cough or congestion.

The Massachusetts study’s results are more damning than the results of a preliminary report published by the Centers for Disease Control, conducted by researchers at the University of Geneva in Switzerland. The Geneva study compared 12 pediatric patients’ samples to adult samples and found that levels of virus in children and adults were comparable. Still, the Geneva researchers write, their results also show that infected children can transmit the disease.

This story was updated 24 August to reflect new masking guidelines.

Image Credits: Flickr: Jill Carlson, Flickr: Ivan Radic.