Fauci recalls his initial encounter with reports of a mysterious disease that would later become known as AIDS. It began in June 1981, when Fauci read an issue of the Morbidity and Mortality Weekly Report (MMWR) about five healthy men in Los Angeles with an unusual pneumonia called Pneumocystis carinii. Fauci speculated that the cases might be linked to a toxic substance but soon dismissed it as a minor curiosity. A month later, he was alarmed by another MMWR article documenting similar cases among 26 homosexual men in New York, Los Angeles, and San Francisco, some of whom also had Kaposi’s sarcoma—a rare cancer typically seen in immunocompromised patients. Realizing that these cases likely signaled a new infectious disease, he became intrigued.

As the Centers for Disease Control and Prevention (CDC) led investigations into the emerging illness, Fauci decided to change his focus from the immune disorders he had been researching to the new, unexplained syndrome. He built a dedicated team at the NIH to study affected patients, although his decision was met with skepticism from peers, who did not believe the illness was going to be around for long enough to warrant the attention. By late 1981, the scope of the epidemic began to widen, with reports of infections in injection drug users, hemophiliacs, and heterosexual partners, indicating broader transmission than initially thought.