"What we saw was, around Memorial Day, the country started to open up and some states were in pretty good shape and eventually opened very slowly," Jha told host Bill Hemmer. "Other states already had a lot of cases and they opened pretty rapidly, and what I think we're seeing is a mix of some of that higher levels of cases and some outbreaks.
"We've also gotten better on testing," Jha added. "So that explains a little bit. But with these increases, Bill, we're seeing increases in hospitalizations and that's a real concern."
Several states have reported a rise in coronavirus cases, which could intensify as people return to work and venture out during the summer. While the rise is partially attributable to increased testing, experts have warned that some states may have lifted their restrictions too early.
"There's been a few things that have surprised us, certainly surprised me," Jha admitted Monday. "When Georgia opened up, I thought it was a little too early and I was worried [that] we were going to see big increases in Georgia. We didn't.
"So I think we have to keep looking at the data. But as I'm seeing the data, Bill, I am getting worried that there are states where the numbers are increasing pretty fast and we've got to get our arms around it because nobody wants to be in a position where we have to decide whether we need to shut down again."
Jha added that the spikes should not be thought of as part of a "second wave" of the pandemic.
"Before you get to the second wave, the first wave has got to get done," he said. "Remember, what we call the first wave primarily hit a small number of spots: New York, New Jersey, New Orleans, parts of California, Seattle. What we're seeing now is the rest of the country experiencing that first wave.
"And so, I'm worried that we're gonna see lots of cases in in a bunch of states that haven't experienced them. And I'm you know, I agree with ... the White House that we don't want to shut down again. The question isn't, do we want to shut down? The question is, can we get control of the virus?
"If we can get control the virus, we don't have to shut down," Jha added. "Well, that's up to us whether we do the work to do that or not."