A resurgence of COVID-19 next winter could hit the United States health care system even harder than the original outbreak has, the director of the Centers for Disease Control and Prevention (CDC) has warned.

If the virus has a second wave that coincides with the start of flu season — which is responsible for thousands of American deaths per year — then the nation's health care system will likely be even more overwhelmed and under-supplied than it has been during the current outbreak of coronavirus in the U.S., CDC Director Robert Redfield told The Washington Post on Tuesday (April 21).

"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 said. "We're going to have the flu epidemic and the coronavirus epidemic at the same time."

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The first wave of COVID-19, the disease caused by the novel coronavirus, SARS-CoV-2, has already killed nearly 46,000 people across the country since the first known U.S. case was reported in January. The outbreak has overwhelmed hospitals and exposed huge shortages of test kits and personal protective equipment like masks and gowns for health care workers.

Fortunately, Redfield said, the epidemic arrived toward the end of flu season, which usually peaks between December and February, and creates an annual strain on the U.S. health care system. According to official CDC estimates, the flu killed nearly 32,000 Americans in the 2018-2019 season and resulted in half a million hospitalizations. If flu season had peaked at the same time as the COVID-19 outbreak, "it could have been really, really, really, really difficult in terms of health [care] capacity," Redfield said.

That may well be the case this winter, he cautioned, if a second wave of coronavirus hits near the beginning of flu season.

Because a widely available coronavirus vaccine is likely still 12 to 18 months away, preventing a deadly double-outbreak of respiratory viruses from ravaging the country will depend on a combination of other actions. First, Redfield said, state and federal officials must continue to push for social distancing this summer as more businesses and public spaces reopen. Social distancing has had an "enormous impact … on this outbreak in our nation" since the pandemic began, Redfield said, and that will hold true until coronavirus vaccines are widely accessible.

Second, the country needs to massively scale up testing and contact tracing (individuals exposed to infected people) so that new COVID-19 cases can be identified before they become larger outbreaks. And finally, Redfield said, U.S. health officials must spend the summer months persuading citizens about the importance of getting flu shots in the fall, in order to minimize the number of flu-related hospitalizations.

As Redfield puts it, getting a flu vaccination this year "may allow there to be a hospital bed available for your mother or grandmother that may get coronavirus."Updated April 22 at 8:00 p.m. ET: During the President's daily coronavirus briefing, director Redfield clarified his comments to the Post, saying:

"I think it's really important to emphasize what I didn't say. I didn't say [the next wave of COVID-19] was going to be worse. I said it was going to be more more difficult and potentially complicated because we'll have flu and coronavirus circulating at the same time. I want to emphasize we continue to build the nation's public health infrastructure to ensure that we have the capacity to stay in the containment mode."

Originally published on Live Science.