If you run into a left-leaning “consultant” these days, there’s a fairly good chance they used to work for the Obama administration. Scores of federal officials and bureaucrats have resigned or been fired since President Trump’s inauguration, some after realizing their goals were not in line with the new president’s.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, wasn’t one of them. In fact, he seemed surprised at the suggestion that he might do something other than what he’s been doing since he began leading the institute in 1984—trying to protect people from diseases like Ebola, Zika, and HIV.

This is despite the fact that some of Trump’s policy proposals seem to directly contradict his efforts. Trump has proposed cutting funding for a program that provides HIV drugs to people in poor countries by 17 percent. Not long after, six members of the Presidential Advisory Council on HIV/AIDS resigned, citing “a president who simply does not care.”

Repealing the Affordable Care Act—a move Trump has supported—would cut a key infectious disease fund in half. And Trump’s decision to reinstate a law that withholds global-health funding from organizations abroad that “perform or actively promote abortion” could hamper AIDS-relief efforts, as my colleague Joseph Frankel reported. As if that weren’t enough, Trump has also aired anti-vaccine views.

I asked Fauci if he was daunted by all these developments, and if not, how he planned to do his work in spite of them. An edited version of our conversation, which took place at the Aspen Ideas Festival, follows:

Olga Khazan: I know you’ve worked for every administration — you’ve worked for Bush, you worked for Reagan, Obama …

Anthony Fauci: Clinton.

Khazan: Clinton, he was in there too. Given that many civil servants have resigned from the Trump administration … when Trump was elected, did you ever think, “I can’t do this one, I’m going to have to sit this one out?”

Fauci: No, not at all. I am embraced by every administration from Reagan onward because they realize that I speak truth to them even when they don’t like it. Even if ideologically they’re very different. When I’m with Reagan, I told Reagan some of the things that I felt he should do with HIV/AIDS. He didn’t listen to everything. He was a good guy but he was afraid to go public and make the bully pulpit and say, “hey everybody this is a problem, we gotta address it.” However, when I got to George H.W. Bush I became very good friends with him.

When he was vice president, he knew that you had to address the AIDS issue. I was very well-known as the AIDS person of the government because very few people were working on AIDS. And he said, “I want you to teach me about HIV. Show me, show me patients.” He wanted to learn. So it’s my old adage, be nice to everybody in Washington, because one of these days they’re going to be really powerful. So I was nice to the vice president and very soon thereafter he was president, so then I had a friend in the White House. I gained a reputation that I would tell you the truth, even if it was something that you didn’t like.

So the word got out that you call on this guy Fauci, he is completely apolitical, and he’ll give you the advice that you need. So I did it with George H.W. Bush, I did it with Clinton, I did it with George W. Bush and I did it with Obama. I developed the President’s Emergency Plan for AIDS Relief program with Bush. I mean for him to give me the opportunity to go to Africa and put together a $15 billion dollar program, that was really nice. With Obama, I was in the situation room like every week, with Ebola and then Zika and H7N9, potentially pandemic flu.

So when the next president came I’d be more than happy to advise, I’m not gonna say, “no I’m not gonna do that.”

Khazan: How do you stay motivated, since this administration has pretty openly wanted to cut a lot of global-health funding, foreign aid, AIDS research? A lot of the things that you would probably work on.

Fauci: It doesn’t interfere with my motivation. I’m driven by the problems that I have to solve. Sometimes you do it with a lot of resources and sometimes you do it with less resources. I don’t say, “well I’m gonna get out because we have less resources.” And as a matter of fact, we don’t know what the resources are gonna be because we don’t have a budget yet.

Khazan: When you look at things like Zika coming to the U.S., do you consider that to be caused more by climate change and related issues or more by human travel?

Fauci: It’s much, much more human travel. I mean you may increase the range of mosquitoes during a period of time, like at the end of June they may go up to Florida. But the major determinant of Zika in the continental United States is travel-related, people who are infected in South America and Puerto Rico who travel to the United States, and that’s exactly what happened. We had about five to six thousand travel-related cases of Zika that came from South America, Central America, and the Caribbean, including Puerto Rico, and so far we’ve had a total of about 220 locally transmitted cases, meaning people that never left Florida.

Khazan: Is a Zika vaccine ready and deployable right now? Or are we still working on it?

Fauci: We have a DNA vaccine for Zika and it’s of interest. The new vaccine uses platform technology. The idea of growing a virus and having to kill it and then injecting it, that’s so passe, as my daughter says, “so 20th century dad.” You don’t want to do that. What it is right now is that we take platforms like DNA, MRNA, virus vectors, and all you need is to insert the gene of whatever protein you want expressed. In Zika it’s the PREM protein which is the protein in the outer part of the virus. We have done that, done preclinical and animal, gone into phase one and we’re now in phase two in Puerto Rico and in Texas and we’re going into phase 2B in countries in South America depending upon what the burden of Zika is. Going from the time we sequence the Zika virus to the time it went into humans in a phase one study was 3.6 months, which is the fastest in the history of vaccinology. Which tells us we could really cut down that time from when you recognize a new infection to the time you get a vaccine at least ready for trial.

Khazan: What do you anticipate being the next thing like Zika? Or is it impossible to predict?

Fauci: The answer is we don’t know, but there are certain things you need to keep your eye on. For example, will Zika come back in some South American countries where it didn’t hit hard last time? Next December will be the third [hot] season in Brazil. I wouldn’t be surprised if we see more. I wouldn’t be surprised if we see more cases in Puerto Rico as we get into this July and August when it’s moist, humid, and a lot of mosquitoes. So I’m keeping my eye on Mexico and the border between Mexico and Texas, particularly around the Brownsville area, where you always see that jumping over the border of emerging infections. And it could be in Puerto Rico. So I’m not through with Zika.

Then the other thing is what about Yellow Fever in Brazil? If it goes into the aedes aegypti mosquito, will that then become … there are two phases of yellow fever. One is called the sylvatic phase which means that woodsmen go into the woods chop down trees for the lumber, they get bit by a mosquito that bit a monkey, the monkey’s the reservoir, they get yellow fever, they get sick. They either die or they get better. Sometimes those people move into the city, and if they get bit by an aedes aegypti, which really likes to bite humans, and you get yellow fever established in a really populous area, then you have a problem. We could get a lot of yellow fever in South America, travel to the United States, and then you wind up getting that.

So I keep my eye on that. The other thing is flu pandemic. This H7N9 bird flu in China? It jumps from a chicken to a human but it doesn’t efficiently spread at all from human to human. If that starts to evolve, that could be something. So there are always these things that you keep your eye on, but the likelihood is that it’s gonna be something that you and I are not talking about right now.

Khazan: Really?

Fauci: Of course. Whoever would have thought there would have been Zika? Zika was on nobody’s radar screen.

Khazan: I would think, well, you would have …

Fauci: I was thinking about Zika, but we did not know that it caused congenital abnormalities, but it was big. So there was an outbreak of Zika in the Yap islands in 2007. There was another outbreak in French Polynesia 2013. So you could have said, “Tony why didn’t you start making a vaccine in 2013?” Because I didn’t think it was a particularly important disease. It was trivial. Eighty percent of the people didn’t get symptoms, the 20 percent that did get symptoms got mild symptoms. They got conjunctivitis, rash, fever, myalgia, it went away in five to seven days, and they were done. Then, when you go to a big country like Brazil, where you have hundreds of thousands of cases, then you start to see something that’s really worrisome, namely pregnant women get infected and they have a 10 percent chance of having microcephalic baby. So that’s when we realized we’re dealing with a very serious disease.

Khazan: What was the $1.9 billion dollars that President Obama had asked Congress for Zika for, since there’s no cure and it’s spread primarily by people traveling from other countries. What is that money primarily used for?

Fauci: We feel that if we don’t stop it in South America, it inevitably is going to come to our territories, including Puerto Rico and even to the southeastern part of the United States. So a considerable amount of money will go to the CDC to do mosquito control. To do surveillance, to do testing. To determine the natural history. That takes hundreds and hundreds of millions of dollars. So the CDC got a lot of money. USAID got money, NIH got money, FDA got money. We got relatively little. I mean of the Zika amount, we asked for $197 million and we got $152. And we’re working on a vaccine, on drugs and stuff, but a lot of it was public-health provisions. Mosquito control became very, very important. We were doing a lot of spraying in Puerto Rico, we were doing a lot of mosquito control, such as genetically modified mosquitoes, all that costs money.

Khazan: Do you work on the anti-vaccine movement at all?

Fauci: We don’t work on it but we try and do public relations discussions. I do TV, I do radio, I do interviews like this, to make it clear that I can understand how people are concerned, but the facts, the science, countless amounts of data from independent, non-biased people indicate that A) vaccines are safe, B) they do not cause autism, and C) they don’t cause those other things that people think they do.

Khazan: Have you found any messages that resonate with people, that actually change people’s minds about not vaccinating?

Fauci: Yes. There is a core of people who no matter what you say, they will not believe you. They are convinced that vaccines are dangerous or they feel they don’t want to take the risk of their child, even though there’s two reasons to give vaccine: one is to protect your child, the other is a duty that you have to society to keep society protected.

Yet there is also a pretty good core of people who if you explain it to them in a non-pejorative way … one of the things that I’ve learned works is that you don’t criticize people. That’s not the way to their hearts. And you’ve gotta approach it in saying that you could understand their concern, but these are the reasons. In the realm of science, you have to rely on the evidence base. You can’t guess, you can’t do spurious things.

Khazan: You said you are known for telling people hard truths. What’s a hard truth that you have had to tell this administration, or might have to tell them?

Fauci: I’m all ready doing it. There is a concern that, are the data regarding safety of vaccines really strong data? And I’m not talking about the president himself, I’m talking about the people around him. And I’ve already met with a couple of people who were sent to me by the administration to try and convince them or to at least talk to them about what’s the situation, because they believe that vaccines are dangerous. Vaccines do not cause autism, period. And that’s it. Now if members of whatever administration — this administration, the last administration, or the next administration — I’ll have to just tell them what I know based on evidence. Whether they believe it or not, it’s up to them.