Forty years ago this month, the U.S. Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report noted a rare lung infection among five otherwise healthy gay men in Los Angeles, Calif. Though they didn’t know it at the time, the scientists had written about what would turn out to be one of the historical moments that launched the Acquired Immunodeficiency Syndrome (AIDS) epidemic.

Since then, HIV/AIDS has killed an estimated 35 million people, including 534,000 people in the U.S. from 1990 to 2018 alone, according to UNAIDS, making it one of the deadliest epidemics in modern history. Over the last year-plus, another outbreak—the COVID-19 pandemic—has also extracted a terrible toll, killing more than 600,000 in the U.S. and more than 3.7 million globally.

For some of those who survived or otherwise had their lives irrevocably changed by HIV/AIDS, COVID-19 has been particularly challenging—those with HIV/AIDS may be at greater risk for severe conditions connected to infection with the coronavirus; and people with weakened immune systems may not get the same level of protection from vaccination as others. Over the last two months, TIME has been speaking with HIV/AIDS survivors about their experiences both with that epidemic and with COVID-19, and about the historical parallels between the two outbreaks. Their stories have been lightly edited for length and clarity.