Coronavirus could prove “more difficult” in the winter than the current wave of the pandemic, and protests against stay-at-home orders are “not helpful,” the director of the Centers for Disease Control and Prevention said Tuesday.

Dr. Robert Redfield, in an interview with The Washington Post, said a wave of coronavirus in the winter mixed with the spread of the seasonal flu could overwhelm the health system.

“There’s a possibility that the assault of the virus on our nation next winter will actually be even more difficult than the one we just went through,” Redfield told WaPo. “We’re going to have the flu epidemic and the coronavirus epidemic at the same time.”

The Trump administration is working to ramp up testing across the United States to track and trace clusters of coronavirus in order to prevent larger outbreaks. Most health experts expect that coronavirus will begin transmitting again after social distancing measures are relaxed over the next couple of months.

The White House coronavirus task force set up guidelines to begin relaxing restrictions in states where the virus has started to subside. Some health experts have expressed concern that a premature return to normalcy will lead to more outbreaks of the virus across the country.

Most experts expect the virus to begin transmitting again once businesses reopen, but the Trump administration hopes to use widespread testing to spot coronavirus clusters before they turn into larger outbreaks.

Dr. Deborah Birx, the White House coronavirus task force coordinator, was asked about Redfield’s remarks about a press briefing on Tuesday.

“I don’t know if it will be worse, I think this has been pretty bad. When you see what happened in New York, that was very bad,” she told reporters.

“I believe that we’ll have early warning signals from our surveillance that we’ve been talking about in these vulnerable populations. We’re going to continue that surveillance from now all the way through to be able to give us that early warning signal.”