A new study finds that adults aged 20-49 were responsible for most virus transmission last year, even after schools reopened in the fall. The study, published in Science, challenges the notion that non-vulnerable people can go about their normal lives, while vulnerable people self-isolate. Three-quarters of new infections originated from adults 20–49 until mid-August of last year, with adults 35–49 contributing the most to spread. In October, after a large portion of U.S. students returned to school, this age group was still responsible for about 72 percent of new infections. The study estimates that school reopening’s increased total infections by about 26 percent as of October, and deaths by about six percent–because children and teenagers spread the virus to adults, who are “more transmission efficient.”
