The model updated this week by the University of Washington — the one most often mentioned by U.S. health officials at White House briefings — predicts daily deaths in the U.S. will hit a peak in mid-April then decline through the summer.

Their latest projection shows that anywhere from 49,431 to 136,401 Americans will die in the first wave, which will last into the summer. That’s a huge range of 87,000. But only a few days earlier the same team had a range of nearly 138,000, with 177,866 as the top number of deaths. Officials credit social distancing.

The latest calculations are based on better data on how the virus acts, more information on how people act and more cities as examples. For example, new data from Italy and Spain suggest social distancing is working even better than expected to stop the spread of the virus.

The time it took for the epidemic to peak — that is, for those deaths to start declining — was shorter in those Italian and Spanish cities than it was Wuhan, China, said Dr. Christopher Murray of the University of Washington, who developed the model.