But even a virus with a fatality rate less than 1% presents a formidable threat, Rivers says. "That is many times more deadly than seasonal influenza," she says.
The new evidence is coming from places such as Indiana, which completed the first phase of a massive testing effort early in May.
The governor wanted basic information, such as how many people had been infected, and how many would die.
"It doesn't capture the vast number of people out there who might be infected but not seeking medical care," he says.
Preliminary results showed that the coronavirus had infected about 3% of the state's population, or 188,000 people.
"That 188,000 people represented about 11 times more people than conventional selective testing had identified in the state to that point," Menachemi says.