The nation is already reporting more than 70,000 cases a day, according to The Washington Post’s rolling seven-day average — an increase of nearly 60,000 in the daily average in less than six weeks. Cases, measured as that rolling average, have risen to levels last seen in February.

Justin Lessler, a University of North Carolina epidemiology professor who assisted in coordinating pandemic forecasts through the COVID-19 Scenario Modeling Hub, said he was “quite concerned. … It worries me that we may have been too optimistic” in projecting lower caseloads into the fall.

The seven-day average of cases nationwide has risen by about 60 percent in the past week alone. Daily hospitalizations rose by roughly 40 percent and deaths rose almost 30 percent, now averaging more than 300 each day.

“It is getting worse, and at least as of right now, it is not really slowing down in the U.S.,” said David W. Dowdy, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.