Dr. Anthony Fauci has advised six presidents on deadly viruses dating back to Ronald Reagan. But this is the first time he's witnessed a president who is actually infected with a potentially lethal disease.

In an interview with Spectrum News, the director of the National Institute of Allergy and Infectious Diseases says President Donald Trump is not out of the woods.

"Even though he feels good now, he's only several days into the illness. You have to be careful,” Dr. Fauci said. “I think it's important to point out that you don't want to minimize this disease or trivialize it. It's a very serious disease."

It's true that younger people have a far less chance of getting seriously ill than the elderly or people who have underlying conditions, but one should not assume that they're dealing with a trivial disease. There have been more than 210,000 deaths in the United States and more than seven million infections globally.

“Over a million deaths, Dr. Fauci told us. “This is serious business. You can't trivialize it.”

On Monday, President Trump left Walter Reed Medical Center and returned to the White House. He said the Regeneron treatment helped him feel better. Dr, Fauci explained how it works.

“Regeneron Monoclonal Antibody is now in clinical trials to determine its safety and efficacy. The other drugs that the president got, the remdesivir and the dexamethasone, have clearly been shown to be effective decreasing the time to improvement and discharge from the hospital, and with the dexamethasone to reduce the 28-day mortality,” Dr Fauci said.

This week, Dr. Fauci predicted the U.S. could possibly see more than 100,000 to 200,000 more deaths from COVID-19 this fall and winter if the nation doesn't double down on prevention methods.

“What can we do to avoid that? What we can do is the public health measures that I talk about all the time, the simple things: keeping distance, wearing a mask, avoiding crowds,” Dr. Fauci said. “They seem very simple. Do you think you can avoid just by doing that? And the answer is absolutely yes!”

In New York City, a rise in cases in certain hot spots has led to the closure of nonessential businesses and roughly 300 schools in parts of Brooklyn and Queens.

“You don't want to lock down completely again,” Dr. Fauci said. "It's so difficult from an economic standpoint of schools - from the standpoint of just the mental health of the people of New York. But you've got to double down on some of the public health issues. Make sure people are universally wearing masks.”

And then there is the debate over whether we are in the first wave or have entered the second wave. Dr. Fauci provided some clarification:

“Well, when you're in a first wave it's almost irrelevant because when you think of 40,000 new infections a day, I don't think in terms of second waves. I think in terms of first waves getting worse. Because you say second wave...we’ve never gotten out of the first wave - we're stuck at 40,000 new infections a day."

Flu season typically starts this month, and there’s talk of a “twindemic” as the weather turns colder, which is why Dr. Fauci said the flu shot is more important than ever

“Since the early signs and symptoms of COVID-19 are very similar to influenza - flu-like syndrome - there are diagnostic tests for both of these so if you have the symptoms and you go to a physician, they very likely will be able to distinguish between the two.“