https://www.scientificamerican.com/article/lessons-for-covid-19-from-the-early-days-of-aids/

Thirty-six years ago, we were, like today, in the midst of a new and still somewhat mysterious global pandemic. In the U.S. alone, more than one million people were infected with HIV, and 12,000 had already died of AIDS. At the time, we were just beginning to understand how the virus worked. But that didn’t stop some leaders from making wildly optimistic claims about an AIDS vaccine being delivered within two years.

Now, with COVID-19, we are in a remarkably similar spot: 2.7 million people have been infected across the U.S., and 128,000 have died of the disease. Despite our limited understanding of how the novel coronavirus works and what it does to the human body, many are putting what I consider a disproportionate amount of faith in the possibility of a COVID-19 vaccine by 2021. My feelings today echo my feelings a third of a century ago: yes, a vaccine may be possible, but it is by no means a certainty.