In a typical year, scientists discover two or three viruses that have never been seen in people before. The number fluctuates, but the trend has been fairly steady since the 1960s.
Most of these viruses attract little attention, and my colleagues and I have often had to search through old medical papers to find any mention of them. Some viruses disappear entirely and are all but forgotten. At the other extreme, the discovery of HIV-1 in 1983 and Sars-CoV-2 in 2020 presaged the Aids and COVID pandemics, respectively. Both have killed tens of millions.
