Of all the coronavirus’s qualities, perhaps the most surprising has been that seemingly healthy people can spread it to others. This trait has made the virus difficult to contain, and continues to challenge efforts to identify and isolate infected people.

The coronavirus pandemic’s toll on the nation’s economy became emphatically clearer Thursday as the government detailed the most devastating three-month collapse on record, which wiped away nearly five years of growth.

Gross domestic product, the broadest measure of goods and services produced, fell 9.5 percent in the second quarter of the year as consumers cut back spending, businesses pared investments and global trade dried up, the Commerce Department said.

 The number of people infected with the coronavirus in different parts of the United States was anywhere from two to 13 times higher than the reported rates for those regions, according to data released Tuesday by the Centers for Disease Control and Prevention.

The findings suggest that large numbers of people who did not have symptoms or did not seek medical care may have kept the virus circulating in their communities. The study is the largest of its kind to date, although some early data was released last month.

“These data continue to show that the number of people who have been infected with the virus that causes Covid-19 far exceeds the number of reported cases,” Dr. Fiona Havers, the C.D.C. researcher who led the study, said in an email. “Many of these people likely had no symptoms or mild illness and may have had no idea that they were infected.”