White House adviser Anthony Fauci said Monday that he and other health officials were “always aware” of the protection afforded by COVID-19 natural immunity.

“We were always aware that if you get infected, you have a degree of protection against reinfection,” Fauci remarked in response to a question from a reporter with The Hill.

He later said that the protection afforded by natural immunity and vaccination “wanes over a period of time,” which is “very, very different” from other infections like polio, smallpox, and measles.

“The people who were talking about natural immunity were making an assumption … that once you get infected, you are essentially protected very, very well for a period of time,” Fauci said. He claimed that individuals who have been infected and vaccinated have the best protection, describing that phenomenon as “hybrid immunity.”