As coronavirus deaths soar across the country, deaths in communities that are home to colleges have risen faster than the rest of the nation, a New York Times analysis of 203 counties where students compose at least 10 percent of the population has found.

In late August and early September, as college students returned to campus and some institutions put into place rigorous testing programs, the number of reported infections surged. Yet because serious illness and death are rare among young coronavirus patients, it was unclear at the time whether the growth of infections on campus would translate into a major health crisis.

But since the end of August, deaths from the virus have doubled in counties with a large college population, compared with a 58 percent increase in the rest of the nation.

Few of the victims were college students but, rather, older people and others living and working in the community.

Since the pandemic began, a Times survey has identified more than 397,000 infections at more than 1,800 colleges and universities. Those cases include more than 90 deaths involving college employees and students.

The link between an outbreak at a college and a coronavirus death in the wider community is often indirect and difficult to document, according to public health experts, especially without extensive contact tracing, which many local health departments in the United States lack resources to pursue.

But researchers have begun finding evidence of ties to college students. Using genetic sequencing to track cases around the University of Wisconsin-La Crosse, Paraic Kenny, a cancer geneticist at the Kabara Cancer Research Institute of the Gundersen Medical Foundation, has found links between infections at the university and cases and deaths in the surrounding region.

That trend highlighted a central fear of health officials — that young adults with limited symptoms might unwittingly transmit the virus, increasing the possibility it would ultimately spread to someone more vulnerable.

Experts suggest an array of ways such spread might happen, including one simple possibility: More than 1.1 million undergraduates work in health-related occupations, census data shows, including more than 700,000 that serve as nurses, medical assistants and health care aides in their communities.

But spread of the virus may also be more invisible, through layers of separation.

“All it really takes is one cavalier interaction,” said Tali Elfassy, an epidemiologist at the University of Miami.

— Danielle Ivory, Robert Gebeloff and Sarah Mervosh The NYTimes