On June 5, 1981, the US Centers for Disease Control published a 527 word report in its Morbidity and Mortality Weekly Report under the title Pneumocystis Pneumonia, describing cases from Los Angeles. Its lead author was Michael Gottlieb, an assistant professor at the University of California, Los Angeles, working with Wayne Shandera, the CDC's Epidemic Intelligence Service officer in Los Angeles, and colleagues at UCLA and Cedars Mount Sinai Hospital.

The report described five young gay men, aged 29 to 36, who had been treated between October 1980 and May 1981 at three Los Angeles hospitals for Pneumocystis carinii pneumonia, a lung infection that in the United States was seen almost only in people with severely suppressed immune systems. All five had been previously healthy, and all had evidence of cytomegalovirus infection. Two had died by the time the report was published, and the other three died soon after.

The pattern was not limited to Los Angeles. New York dermatologist Alvin Friedman-Kien alerted the…