So much for kids not spreading Covid:

Stumpfan · Jun 2, 2023

Of all households transmissions, 70.4% began with a child, with the proportion fluctuating weekly between 36.9% and 87.5%. Pediatric transmissions reached a high of 68.4% the week of September 27, 2020, and fell to a low of 41.7% the week of December 27, 2020 (0.61 times less frequent). The next high was 82.0% the week of May 23, 2021, which stayed stable until June 27 (81.4%) and then declined to 62.5% by August 8 (0.77 times less frequent).

The percentage of household transmissions beginning with a child then rose to 78.4% by September 19, hovering there until November 14 (80.3%) and then dropping to 54.5% the week of January 2, 2022 (0.68 times less frequent). By March 6, the proportion rose to 83.8%, fell to 62.8% the week ending July 24 (0.75 times less frequent), and then climbed to 84.6% the week of October 9.

In-person school contributed to transmission

"More than 70% of transmissions in households with adults and children were from a pediatric index case, but this percentage fluctuated weekly," the study authors wrote. "Once US schools reopened in fall 2020, children contributed more to inferred within-household transmission when they were in school, and less during summer and winter breaks, a pattern consistent for 2 consecutive school years."

The researchers said the finding that pediatric COVID-19 transmission was negatively correlated with new community cases during most of the pandemic is consistent with that of a previous study.

Once US schools reopened in fall 2020, children contributed more to inferred within-household transmission when they were in school, and less during summer and winter breaks.

"When the incidence of COVID-19 increases, adults in the community are at higher risk of infection; this may increase the likelihood that adults become the index case in a household transmission and explain the negative correlation we observed," they wrote. "Also, when the COVID-19 incidence is low, overall use of nonpharmaceutical interventions might decrease, leading to increased incidence of non–SARS-CoV-2 pathogens which may be more common in children."