How could that be? There are two main reasons.

One, the fact that more people may have already had the virus also suggests that it’s more contagious than the initial numbers suggested — that any one person with the virus tends to pass it to a greater number of others. And if it’s more contagious, it may be harder to contain in coming months. As society begins to reopen, the virus could spread more quickly. The number of Americans who get it before a vaccine is developed would then be larger.

Two, even if the death rate is lower than feared, it’s still very high. “It is still, with these new findings, many times more deadly than influenza,” Caitlin Rivers, an epidemic researcher at Johns Hopkins University, told me. The best current guess is that the death rate for coronavirus is about five times higher than that of seasonal influenza.

A few basic calculations show how scary a 0.5 percent death rate is. If about one in three Americans ultimately get the virus — or 110 million people — more than 500,000 would die. If 200 million people get it, 1 million would die.

Ezekiel Emanuel of the University of Pennsylvania pointed out to me that about 20 percent of virus fatalities so far in the United States have been among people aged between 35 and 64. If the total number of deaths ends up in the ranges I’ve mentioned here, the virus could end up being the No. 1 killer of people in that age group, surpassing both cancer and heart disease.

The latest news, Emanuel said, “doesn’t make any of the goals you want to reach easier.”

As I’ve written before, it’s likely that we have a long and very difficult fight ahead of us.