Day 178: Still Not the Kids

It's hardly been a week since the New York Times ("all the news that's unfit to print") misinterpreted a Korean study to blame older children for transmitting coronavirus, even though the lack of transmission and illness in children is one of the most obvious and unusual qualities of the new SARS. Not one but two studies are out in preprint showing that children actually impede transmission.

Dyke wardens or Drivers? Why children may play an attenuating role in the spread of SARS-CoV-2 came out in mid-July. The authors note the low likelihood of asymptomatic spread, as well as children's higher likelihood of being uninfected or asymptomatic, and that at the seven-month point in the pandemic, we know kids just don't get infected; they weren't just escaping exposure temporarily. Even teens are less likely to ever show symptoms than adults.

When children and young adults do show symptoms, their symptoms are milder and briefer than in adults, which makes the children that much less likely to spread the disease, and, perhaps more importantly, likely to spread it at lower doses, resulting in milder cases for those they do infect. Children also seem less likely to catch the virus in the first place. Their immune systems are better, or perhaps just busier with the many other viruses they're constantly spreading around.

It's not an experimental report, but the authors do note plenty of circumstantial evidence for their theory. Most notably, SARS and MERS were also unlikely to cause symptoms in or to be spread by children. At the country level, more youth-filled countries have experienced milder pandemics than elsewhere. They admit that school closures may have impeded the spread, though they find little proof in the literature for the efficacy of locking down the children.

The other preprint, On the effect of age on the transmission of SARS-CoV-2 in households, schools and the community, came out Friday. The authors dig an overwhelming number of transmission rate estimates and seroprevalences out of the literature. Although many of the studies also found low transmission rates among teens, their final conclusion is that the under-10 set are at most half as susceptible as adults, but pre-teens and teens should be treated with caution along with all adults under 35, because of their similarities to that group's high spreading potential.

P.S. Massachusetts cases are up a quarter of a percentage point today.