The coronavirus pandemic in the US was mainly caused by young and middle-aged people, while the elderly were mostly killed.
Driving the news: Adults aged 20-49 were responsible for the vast majority of virus transmission last year, even after schools reopened in the fall, according to a new study published in Science.
Why it matters: The US vaccination efforts are racing to keep up with the spread of new, more communicable variants of the virus. Millions more Americans could be infected before a substantial portion of the population is vaccinated, making transmission patterns very relevant.
- The idea that non-vulnerable people can live their normal lives while vulnerable people isolate themselves has not been confirmed in the US.
In numbers: Three quarters of the new infections came from adults aged 20-49 up to mid-August last year. Adults 35-49 contributed the most to the spread.
- In October, after a large portion of American students returned to school, this age group was still responsible for it about 72% of new infections.
- The study estimates that the number of school reopenings as of October increased overall infections by about 26% and deaths by about 6% – as children and teens spread the virus among adults, who are “more efficiently transmitted.”
Between the lines: Young and middle-aged adults “naturally have the most contact with other adults 20 and older who are more susceptible” to the virus, and were more mobile from April onwards, according to the study.
It comes down to: “This suggests that additional interventions in adults aged 20-49, including rapid mass vaccination if vaccines have been shown to block transmission, could control the resurgence of COVID-19 epidemics,” the authors conclude.