The coronavirus pandemic in the United States was caused mainly by young and middle-aged people, while it mainly killed older people.
Driving the news: Adults aged 20 to 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 effort is running to keep up with the spread of new, more communicable variants of the virus. Millions of other Americans can be infected before a substantial part of the population is vaccinated, making patterns of transmission deeply relevant.
- The notion that non-vulnerable people can live their normal lives, while vulnerable people isolate themselves, has not been confirmed in the USA
By the numbers: Three-quarters of the new infections originated in adults aged 20 to 49 until mid-August last year. Adults aged 35 to 49 contributed most to dissemination.
- In October, after a large proportion of US students returned to school, that age group was still responsible for about 72% of new infections.
- The study estimates that the reopening of schools increased the total number of infections by about 26% from October and deaths by about 6% – because children and adolescents spread the virus to adults, who are “more efficient at transmission” .
Between the lines: Young and middle-aged adults “naturally have more contact with other adults aged 20 and over who are more susceptible” to the virus, and they were more mobile as of April, according to the study.
The final result: “This suggests that additional interventions for adults aged 20-49, including rapid mass vaccination if vaccines block transmission, could bring resurgent COVID-19 epidemics under control,” conclude the authors.