New Evidence Suggests Young Children Spread Covid-19 More Efficiently Than Adults

(Posted on Monday, August 3, 2020)

Two new studies, though from different parts of the world, have arrived at the same conclusion: that young children not only transmit SARS-CoV-2 efficiently, but may be major drivers of the pandemic as well.

The first, which was published in JAMA yesterday, reports findings from a pediatric hospital in Chicago, Illinois. The second, a preprint manuscript awaiting peer review, was conducted in the mountainous province of Trento, Italy.

The Chicago study examines the concentration of the SARS-CoV-2 in the nasopharynx, or the upper region of the throat that connects to the nasal passages, of children and adults. According to the results, children 5 years and younger who develop mild to moderate Covid-19 symptoms have 10 to 100 times as much SARS-CoV-2 in the nasopharynx as older children and adults.

Whenever these young children cough, sneeze, or shout, they expel virus-laden droplets from the nasopharynx into the air. If they have as much as one hundred times the amount of virus in their throat and nasal passages as adults, it only makes sense that they would spread the virus more efficiently. The study also shows that children from the ages of 5 to 17, also with mild to moderate Covid-19 symptoms, have the same amount of virus in the nasopharynx as adults age 18 and above.

The authors conclude it is likely that young children, while not as prone to suffering from Covid-19 infection, still drive its spread—just as they do with several other respiratory diseases.

The second manuscript reports the results of an extensive contact tracing study conducted in Trento, an autonomous region in Northern Italy. Despite a total lockdown that began in March with the closure of schools, universities, and all businesses except grocery stores, pharmacies, and newsstands, for more than a month the number of cases rose exponentially.

The researchers found that although young children had a somewhat lower risk of infection than adults and were less likely to become ill, children age 14 and younger transmit the virus more efficiently to other children and adults than adults themselves. Their risk of transmitting Covid-19 was 22.4 percent—more than twice that of adults aged 30 to 49, whose rate of contagiousness was about 11 percent. “Although childhood contacts were less likely to become cases,” they wrote, “children were more likely to infect household members.”

The Chicago study also found that its youngest participants were the most efficient transmitters of the disease, citing respiratory syncytial virus as an example of another infectious disease for which this has been the case.

Both studies spell serious implications for countries contemplating whether or not to reopen schools in the face of lingering and out-of-control outbreaks, the United States included. Even if children are required to keep their hands to themselves, refrain from sharing toys and supplies, and wear masks at all times, we can’t realistically expect them to follow such rules without fail. So long as misbehavior is a possibility, so too is the rampant spread of infection.

If children from ages 5 to 17 are as or possibly even more contagious than adults, then opening schools in areas where daily rates of infection remain moderate to high is extremely risky and unwise. The measures we deploy to contain the spread of Covid-19 in our schools and our communities must take the entire population into account—children age 18 and below included.

Correction (8/5/20): A former version of the article stated that the Trento study found that children were the most efficient transmitters of the disease, citing RSV as an example of another infections disease for which this has been the case. It was actually the Chicago study that reported this finding. The article has been corrected to reflect this fact.

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Originally published on Forbes (July 31, 2020)