Why more young people are getting sick in the latest Covid-19 outbreaks

At the beginning of the coronavirus outbreak in the US, most Covid-19 cases seemed to be in older folks, who were getting very sick — an artifact of who was getting tested at the time.

But now, especially in states where Covid-19 cases have been rising in June and July, the median age has been dropping.

“We are seeing it in a much younger group, of 20- to 40-year-olds,” compared to the earlier stage of the pandemic, says Thomas Tsai, a health policy expert and surgeon at the Harvard T.H....