The 1977 flu pandemic was very likely a lab escape. From the NEJM: > The reemergence was probably an accidental release from a laboratory source in the setting

The 1977 flu pandemic was very likely a lab escape. From the NEJM: > The reemergence was probably an accidental release from a laboratory source in the setting of waning population immunity to H1 and N1 antigens https://www.nejm.org/doi/full/10.1056/NEJMra0904322 https://www.nejm.org/doi/full/10.1056/NEJMra0904322 About 700k people died worldwide. That's more than a typical flu season but not grossly so, and it's impossible to say with certainty what kind of flu season would have occurred naturally without the escape. https://nouvelles.umontreal.ca/en/article/2018/01/19/you-re-more-likely-to-die-from-the-h1n1-flu-if-you-were-born-in-1957/ https://nouvelles.umontreal.ca/en/article/2018/01/19/you-re-... SARS-CoV-2 is certainly worse. The 1977 flu pandemic is still a lot of deaths, though, and surprisingly little-known.