WASHINGTON — The walls in Dr. Anthony S. Fauci’s home office are adorned with portraits of him, drawn and painted by some of his many fans. The most striking one is by the singer Joan Baez. The two of them, he said, “have become pretty good friends over the years.”

Dr. Fauci seemed a little uncomfortable with people knowing about the pictures. He said that previously, when they were captured on camera, the “far right” attacked him as an “egomaniac.” If someone goes to the trouble of sending him a portrait of himself, he said, he would “feel like I’m disrespecting them” if he discarded it.

It was a revealing glimpse into the psyche of America’s most loved and hated doctor as he wraps up more than half a century of government service at the National Institutes of Health. After Saturday, Dr. Fauci, President Biden’s chief medical adviser and for the past 38 years the director of the N.I.H.’s National Institute of Allergy and Infectious Diseases, will no longer be a federal employee.

Dr. Fauci, who turned 82 on Christmas Eve, said he may be retiring, but he is not going away. He hopes to do some public speaking, become affiliated with a university and treat patients if it has a medical center. He intends to write a memoir, he said, and he wants to encourage people to pursue careers in science, medicine and public service.

Republicans, who will take control of the House early next month, will see to it that he does not slip out of the public eye. They have promised to investigate his handling of the coronavirus pandemic and to call him to Capitol Hill to testify. He says he has every intention of showing up and has nothing to hide.

From the AIDS epidemic to Covid-19, Dr. Fauci has been the public face of American science for decades, advising seven presidents along the way. In late November, The New York Times spoke to him at his home office in Washington about his career and his plans for the future. This interview has been edited and condensed.

You have said that you’re retiring from government service but that you’re going to prepare for a “next chapter.” So what’s the next chapter?

That’s a good question. Since I can’t negotiate any details of my post-government life for ethical reasons and conflicts of interest, I’m doing something that is unusual for me, which is not knowing exactly what the details of the next step are going to be. But I decided that I wanted to have a few years outside of government to pursue things that are commensurate with my stage in life.

Namely, I’m going to be 82 years old in a month. And what do I have to offer? Is it more important for me to do yet again another experiment or do yet again another clinical trial, or would it be more important to utilize the benefit of my experience by writing, by lecturing, by getting involved in advisory issues — and importantly, which I really feel strongly about, is to maybe inspire younger people to either go into medicine and science, or, for the people who are already in medicine and science, to maybe consider a career in public service.

When you think about a memoir, how do you envision it? Is there a separate book about Covid?

What I would like to do is make it a real memoir, which is a life story of which Covid is a part. Because if you look at what Tony Fauci was and is, Tony Fauci is not defined by Covid. I would much rather give a story of the whole me, from the time I grew up in the streets of Brooklyn to where I am right now. But I don’t know. I’ve never written a book before.

Beyond looking forward for you, I also want to look forward for the country. What do you think are the biggest health challenges we face?

Unfortunately, I have lived through, and the country and the world has lived through, a series of emerging and re-emerging infections, some of which had profound global impact and some of which have been curiosities and some of which have been regionally impactful. I don’t think it’s going to stop.

Are there other threats that you think about beyond infectious disease threats?

What really, really concerns me is the politicization of public health principles. How you can have red states undervaccinated and blue states well vaccinated and having deaths much more prevalent among people in red states because they’re undervaccinated — that’s tragic for the population.

You’ve worked for seven presidents. Do you have any favorites?

No, I would not discuss favorites. That would not be appropriate.

But certainly Donald Trump must have been the most challenging president.

It was obviously challenging because I have said — and I’ll say it to you — I have a great deal of respect for the office of the presidency of the United States. And I have had the opportunity to tell presidents things that sometimes they may not want to hear, but they took what I said seriously and respected me for giving them the straight scoop.

I did not like nor seek out a position of having to publicly contradict a president of the United States. The far right seems to think I did that deliberately and took pleasure in it. I did not. I felt very, very pained at having to get up in a public press conference and contradict what he says about hydroxychloroquine, contradict what he says about the virus is going to disappear like magic. But I had to do that for my own personal and professional integrity and for fulfilling my responsibility.

My primary responsibility is to the American public. I serve the public; I don’t serve a political party. I’m completely nonpolitical.

Are you registered as an independent?

Yes, I am.

House Republicans will bring you in to testify. Are you prepared for that?

I have no problem testifying before the Congress. I have nothing to hide. I could easily explain and justify everything I’ve done. So they’re making a big to-do about it, but I respect the concept of oversight.

Are there lessons that you think we’ve learned from Covid that, going forward, we should act on?

I look at preparedness and response to the outbreak in two major buckets. One is the scientific bucket, and one is the public health bucket.

If you look at what the major overriding success story of the pandemic has been, it’s the scientific response, the years of investment in basic and clinical research that led to the absolutely unprecedented feat of going from the recognition of a brand-new virus in January of 2020 to doing massive clinical trials to getting the vaccine proven to be safe and effective and in the arms of people within 11 months. That was a major success.

What was not so successful was the public health response. We had antiquated systems. Things were not online or computerized. People were using fax machines. You can’t do that when you’re going to have a response to a pandemic.

So the lesson is continue to support the basic and clinical science, because we’re going to need it, and try and strengthen our domestic and global public health infrastructure.

Reading between the lines there, it might be said, “Tony Fauci did a great job, but the C.D.C. didn’t do such a good job.”

No, that’s not me. I don’t criticize them. But we did — the scientific community did a great job on this. We did.

If you had, let’s say, another 10 years in your job, what are the things that you would focus on? Would it be an AIDS vaccine? Are there some big unrealized goals?

It would certainly be optimization of AIDS therapy, perhaps with a cure. I would love over the next 10 years to apply the new technologies that proved so successful with Covid to get a vaccine for malaria and for tuberculosis.

What about you do people not know? You’re such a public person.

They don’t know hardly anything about the physician aspect of me and how sensitive I am and empathetic towards illness and suffering.

Will you continue to treat patients?

Well, it depends on what institution I hook up with.

You’re retiring from government service. Your ties are being cut with N.I.H. and you’re packing up your office there. How is that for you?

It’s sort of a strange feeling, because I’m so busy. I was just on this Zoom with the White House about a press conference that I’m going to be on. I’m so busy I can’t think about stepping down, and the thing that’s sort of intimidating is that I’ve got to get all that stuff out of my office pretty quickly.

Do you think you’ll donate your papers?

All of my papers are going to go to the Library of Congress and to the National Archives.

I’m sure there are television networks that would like you to be a commentator or work with them. Is that in your future? Will we still see you on TV?

You’ll still see me on TV if they want me on, but I’m not going to make TV a professional aspiration.

I want to ask a little bit more about the politicization of science. How do you think we could come back from this deep hole that we seem to be in?

I don’t know what the mechanism is, but hopefully people will realize that this is detrimental to what we all care about. We love our country. We care about family and values. Maybe it’s naïve. I don’t think it is. I’m not a naïve person. I’m an optimist, but I’m a cautious optimist. I just hope that the better angels in people will prevail.