Accidental Virus Release May Have Triggered Mysterious 1977 Pandemic

Was it simply a coincidence that within months of Pvt. Lewis' death from H1N1 swine flu, a heretofore extinct H1N1 influenza strain suddenly reentered the human population? Influenza virologists around the world had for years been using freezers to store influenza virus strains, including some that had gone extinct in the wild. Fears of a new H1N1 swine flu pandemic in 1976 in the United States had prompted a worldwide surge in research on H1N1 viruses and vaccines. Years after the reemergence, Palese, the microbiologist, reflected on personal conversations he had at the time with Chi-Ming Chu, the leading Chinese expert on influenza. Palese wrote in 2004 that "the introduction of the 1977 H1N1 virus is now thought to be the result of vaccine trials in the Far East involving the challenge of several thousand military recruits with live H1N1 virus."

https://www.sciencealert.com/accidental-virus-release-may-have-triggered-mysterious-1977-pandemic