Are we entering the pandemic’s ‘fourth wave’? Experts disagree.

By now, this is a familiar script. But this time around, the country’s leading epidemiologists disagree about what to call this latest phase of the pandemic. Is the United States on the cusp of a “fourth wave”? Or are we instead seeing the last gasps of a crisis in its 14th month?

Most recently, the debate played out on the Sunday morning news shows. Michael T. Osterholm, an adviser to President Biden’s coronavirus task force, said on NBC’s “Meet the Press” that the next two weeks will bring “the highest number of cases reported globally since the beginning of the pandemic.”

“In terms of the United States, we’re just at the beginning of this surge,” said Osterholm, who is also the director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “We haven’t even really begun to see it yet.”

The pandemic has been cyclical, he said. Cases pile up in the Northeast or the Midwest, subside, and then swell in the South.

“And we’re now, I think, in that cycle where the Upper Midwest is just now beginning to start this fourth surge,” Osterholm said, calling Michigan’s latest case numbers a “wake-up call.”

The Great Lakes State has for nearly 50 days reported increasing numbers of coronavirus infections, a trend that ran counter to the nation until recently, according to data tracked and analyzed by The Washington Post. Over the past week, Michigan has reported an average of 6,500 new cases per day, rivaling levels seen during its record-setting winter surge. It has recorded the second-most cases of the variant first identified in the United Kingdom, according to CDC data.

Cases are also on the rise elsewhere. In the Midwest and Plains, Nebraska, Minnesota and Pennsylvania are among the states that have reported large increases. In the Northeast, states such as Delaware, Vermont and Maine have witnessed a similar incline.

By the numbers, this latest upswing is on par with the surge of cases in July. Going into the weekend, the country was reporting more than 65,000 cases per day, a number that didn’t include several states that did not report data on the Good Friday holiday. That figure is roughly the same as last summer’s peak, when soaring case counts were alarming public health officials and overwhelming some hospitals.

“I think that there’s enough immunity in the population that you’re not going to see a true fourth wave of infection,” Gottlieb said. “What we’re seeing is pockets of infection around the country, particularly in younger people who haven’t been vaccinated and also in school-age children.”

Earlier in the week, Anthony S. Fauci, the government’s top infectious-disease expert, also cast doubt on the prospect of another national surge, saying vaccines are the X-factor that was absent during the first, summer and winter waves.

“It’s kind of like a race between the potential for a surge and our ability to vaccinate as many people as we possibly can,” Fauci said in an interview with NPR’s “Morning Edition.” “And hopefully, if you want to make this a metaphorical race, the vaccine is going to win this one.”

Those comments came a few days after Rochelle Walensky, director of the Centers for Disease Control and Prevention, sounded the loudest alarm yet about the coming weeks.

“I’m going to lose the script, and I’m going to reflect on the recurring feeling I have of impending doom,” she said at a White House briefing last week. “We have so much to look forward to, so much promise and potential of where we are, and so much reason for hope. But right now, I’m scared.”

Experts do agree that the trends are troubling and that they can be traced to a convergence of factors: increased spread of the more transmissible variants and a broad loosening of public health measures, such as mask mandates and limits on indoor dining.

Biden pleaded with cities and states that have lifted precautions to reinstate them.

“Please, this is not politics,” he said last week. “Reinstate the mandate if you let it down, and businesses should require masks as well. A failure to take this virus seriously — precisely what got us into this mess in the first place — risks more cases and more deaths.”

Still, there are unanswered questions that continue to complicate the U.S. response. Among the biggest, Gottlieb argued on Sunday, is whether variants of the virus are reinfecting people.

“We should have that information, but we don’t,” added Gottlieb, who has encouraged the CDC to gather data about reinfections. “So there’s a lot we don’t understand about this virus right now.”