Kids play a larger role in community spread of COVID-19 than previously thought, researchers find

In this photo taken on July 9, 2020, a teacher reads to children in a pre-school class in Monterey Park, California. FREDERIC J. BROWN / AFP via Getty Images, File

Researchers at Massachusetts General Hospital are warning that children should not be disregarded as potential silent spreaders of the coronavirus

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In a new study, “Pediatric SARS-CoV-2: Clinical Presentation, Infectivity, and Immune Responses,” published Thursday in The Journal of Pediatrics, researchers at MGH and MassGeneral Hospital for Children found kids play a larger role in the spread of COVID-19 than previously understood. 

The researchers collected nose and throat swabs, as well as blood samples, from the children in the study, gathering the data from patients seeking evaluation for the coronavirus in outpatient clinics and the COVID-19 urgent care clinic, as well as those who were already hospitalized for symptoms potentially related to the virus. In the survey of 192 children, ages 0 to 22, 49 children tested positive for the virus, SARS-CoV-2, which causes COVID-19.

Researchers found there was “significant” overlap in the symptoms of kids presenting with COVID-19 versus other illnesses, which makes it hard to make an accurate diagnosis of the novel coronavirus. But what was surprising to study authors was that the infected children, regardless of their age, had a significantly higher level of the virus in their airways  — more than adults hospitalized in intensive care for COVID-19. 

“These kids had viral loads that were higher, significantly higher, than patients who were hospitalized for COVID,” Dr. Lael Yonker, director of the MGH Cystic Fibrosis Center and lead author of the study, told

The higher the viral load, the greater the risk of spreading the virus to another person. And although kids with COVID-19 are not likely to become as sick from the virus as adults, the study’s data suggests that kids can carry high viral loads, meaning they are more contagious, regardless of their own susceptibility to developing an infection from the virus.


“It does change the way to think about COVID,” Yonker said. “Previously, people thought that kids were spared from COVID, because people have shown — and we’ve shown in the study as well  — that kids have lower viral receptors, meaning they are less likely to have the virus take hold and cause infection. But what we showed is if there is enough virus, you still can get sick and then the viral load doesn’t reflect how sick you are.”

High viral loads were found even in children who were apparently “healthy,” exhibiting few or no symptoms, but were brought in for screening because of possible exposure to the virus. 

“This shows very clearly that kids can spread the virus while they’re asymptomatic,” Yonker said of the study’s findings. 

Earlier in the pandemic, there had been a suggestion that kids were less likely to spread the virus and less likely to bring it into the home. But those findings were related to a time during the pandemic when kids were being kept at home, so their social interactions were lower, Yonker pointed out.

What she and her colleagues found was that 20 percent of the kids exhibiting symptoms of COVID-19 didn’t have a household contact with the illness, indicating they contracted it outside the home. 

“This data speaks to the fact that children are contracting the virus outside of the house and, as time goes, especially with schools being in session, are going to play more significantly into the role of spreading the pandemic,” Yonker said. 


The MGH researchers also found that the high viral loads were found regardless of the age of the patient.

“We included babies who were one month of age, up to 22 years of age, and there was no difference in how much virus they could carry and therefore spread,” Yonker said. “That was the most surprising finding for us.”

With school reopenings, the worry over kids and the role they play in spreading the virus — bringing the infection into their homes — is of particular concern for families in socio-economic groups already hit harder by the pandemic, the researchers noted in their study — especially multi-generational households with older adults at higher risk for serious complications from the virus. In the study, 51 percent of the children with COVID-19 came from low-income communities, compared to 2 percent from high-income communities.

“The potential for spreading the virus without any symptoms is very concerning and is a warning that even though somebody isn’t sick, you should still wear a mask, follow social distancing, and maintain all of the recommendations that are put out to mitigate the spread of the virus,” Yonker said.

The researcher said based on the levels of virus found in children of all ages, the study findings suggest that there should not be any age restrictions in mandates for face coverings. In Massachusetts, children under the age of 2 are exempt from the mask mandate aimed at preventing the spread of COVID-19. 

“There is no age that has a higher likelihood or a lower likelihood of spreading this infection,” she said. 


That especially applies with schools, she said, urging that if and when in-person learning occurs, all the children in the school be required to wear masks. 

The researchers are also raising concerns that simply doing fever checks or monitoring for symptoms will not be an effective way of screening for COVID-19 among children — particularly as colds and the flu begin circulating and with their overlap in symptoms, even with just allergies.

“What we do recommend is wearing masks and optimizing social distancing,” Yonker said of reopening schools. “And when we say wearing a mask, we did find that nasal secretions had a higher viral load than oral swabs. So when a mask is worn, it should be worn over the nose, not just the mouth.”

In light of their findings, the researchers wrote in the study that in addition to those measures, schools could consider screening all students for COVID-19 and establishing routine testing protocols.

“Without infection control measures such as these, there is significant risk that the pandemic will persist, and children could carry the virus into the home, exposing adults who are at higher risk of developing severe disease,” the paper reads. 

Testing would be particularly important in situations where children are not wearing masks, Yonkers said. 

“Screening is expensive, so if you can have social distancing and mask use and optimize remote learning when possible, these are other ways of trying to mitigate the spread of the pandemic,” she said of reopening. 

An estimated 70 percent of public school districts in Massachusetts are planning to bring kids back, at least part time, into classrooms this fall, Gov. Charlie Baker announced Tuesday. The governor has been making his preference known for using in-person instruction as much as possible, while teachers unions and advocates across the state have been pressing for remote learning


Yonker and her colleagues also raised concerns that as more kids get the coronavirus, more cases of Multisystem Inflammatory Syndrome, or MIS-C, a rare systemic infection that can develop several weeks after kids contract COVID-19, will emerge. The syndrome can cause severe complications, including severe cardiac problems. 

In addition to the 49 children who tested positive for COVID-19 in the MGH study, 18 kids developed the late-stage illness MIS-C. The researchers wrote that learning more about the delayed inflammatory response is critical to developing next steps for treatment and prevention. 

“This is a concern to me,” Yonker said of why more work needs to be done to understand the rare syndrome. “Because not all children develop this inflammatory response, but the more children who contract the virus, eventually, the more children will develop this MIS-C.”

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