Dr. Anthony Fauci on Monday doubled down on his claim that people who are attacking him are “actually criticizing science.”

Speaking on the New York Times podcast Sway, Fauci attempted to explain his history of flip flopping, particularly on the use of masks. While he has championed masks throughout the pandemic, even supporting double masking, he privately dismissed the need for basic drug store masks in a February 2020 email to former U.S. Health and Human Services Secretary Sylvia Burwell.

Emphasis added:

Masks are really for infected people to prevent them from spreading infection to people who are not infected rather than protecting uninfected people from acquiring infections. The typical mask you buy in the drug store is not really effective in keeping out virus, which is small enough to pass through the material. It might, however, provide some slight benefit in keep out gross droplets if someone coughs or sneezes on you. I do not recommend that you wear a mask, particularly since you are going to a vey [sic] low risk location. Your instincts are correct, money is best spent on medical countermeasures such as diagnostics and vaccines.

But, according to Fauci, there was “no real evidence that masks worn outside of the setting of the hospital actually worked to protect you” at the time. The data on several factors, he said, changed:

What did we learn in the subsequent month or two when I changed and said, everybody should wear a mask? A, there was no shortage because we found out that cloth masks actually work. Number two, analyses that were published that showed, for the first time, that guess what? Outside of the hospital setting, masks actually work to protect you and to prevent you from spreading. And three, we learned to our horror that about 50% of the infections were being transmitted by people who didn’t even know they were infected.

So that is the reason why I changed my mind. So the people who are giving the ad hominems are saying, ah, Fauci misled us. First, he said no masks, then he said masks. Well, let me give you a flash. That’s the way science works. You work with the data you have at the time. It is essential as a scientist that you evolve your opinion and your recommendations based on the data, as it evolves. That is the nature of science. It is a self-correcting process.

“And that’s the reason why I say people who then criticize me about that are actually criticizing science,” Fauci said. “It was not a change because I felt like flip flopping. It was a change because the evidence changed. The data changed.”

The U.S. National Institute of Allergy and Infectious Diseases director made the same claim earlier this month during an appearance on MSNBC’s Rachel Maddow Show, describing attacks on him as “very much an attack on science.”