KEY POINTS Americans will be faced with two health horrors this winter: the second wave of COVID-19 and a new flu season

Both these killer diseases threaten to overwhelm the U.S. healthcare system in 2021

“It could have been really, really, really, really difficult in terms of health capacity," CDC director says

The U.S. Centers for Disease Control and Prevention (CDC) confirms COVID-19 may return in a "second wave" during this year's flu season, which starts October.

It warns the COVID-19 comeback might be as virulent as its first onslaught, which began when CDC confirmed the first U.S. case of the coronavirus on January 21. But more frightening will be the massive combined casualty tolls that will be inflicted by the simultaneous influenza and second wave COVID-19 outbreaks.

CDC estimates this year's flu season has caused anywhere from 24,000 to 62,000 deaths, 39 million to 56 million illnesses and from 410,000 to 740,000 hospitalizations for the period October 1, 2019 through April 4.

The toll inflicted by COVID-19 on Americans has been much higher in less than four months. The U.S. is reporting 817,006 confirmed COVID-19 cases and 45,226 deaths, as of 23:32 GMT (7:32 pm ET, Tuesday), according to Worldometer. The case toll is up more than 24,200 compared to the day before while there were more than 2,700 additional deaths compared to Monday. There were more than 2.6 million cases and 177,000 deaths worldwide on Tuesday evening.

CDC Director Dr. Robert Redfield warned of COVID-19's horrific return in an interview with The Washington Post.

“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,” said Dr. Redfield.

“And when I’ve said this to others, they kind of put their head back, they don’t understand what I mean. We’re going to have the flu epidemic and the coronavirus epidemic at the same time."

He emphasized two simultaneous respiratory outbreaks will place already overstretched state health systems struggling to cope with COVID-19 under unimaginable strain. Dr. Redfield said federal and state officials need to use the coming months to prepare for what lies ahead.

He said U.S. health officials this summer need to persuade Americans to get their flu shots in the fall. He noted this will be one way the U.S. can minimize the number of people hospitalized from flu.

Dr. Redfield said a flu vaccination, “may allow there to be a hospital bed available for your mother or grandmother that may get coronavirus.”

He said it was lucky COVID-19 swept into the U.S. as the current flu season was waning. He pointed out a severe flu season can strain hospitals and clinics.

Dr. Redfield believes that if the first wave of the COVID-19 pandemic and flu season had peaked at the same time early this year, “it could have been really, really, really, really difficult in terms of health capacity.”

As it stands now, the COVID-19 pandemic is overwhelming more and more hospitals (especially in the cities), and has revealed mammoth shortages in test kits, ventilators and personal protective equipment (PPE) for healthcare workers. More than 9,300 U.S. healthcare workers have been afflicted with COVID-19 while 27 have died, as of last April 15 and this toll is rising daily.

The casualty count was reported by CDC in its first preliminary data on infections among frontline healthcare workers. On the other hand, CDC admitted this data is almost certainly a substantial undercount because most of the people tested in the overall data set (84%) didn't say whether they're a healthcare worker or not.

The data shows three-quarters of the 9,300 healthcare workers taken ill are women. More than a third had some underlying health condition. The median age of these patients is 42. A third of the healthcare workers that died were over 65 years old. Five percent of those hospitalized needed intensive care.

"The increased prevalence of severe outcomes in older (health care providers) should be considered when mobilizing retired (healthcare providers) to increase surge capacity," warned the CDC report.