Strains of viruses used to make smallpox vaccines during the US civil war have been identified from old scabs and blister material stored in historical vaccination kits
Source:
https://www.newscientist.com/article/2249279-smallpox-vaccination-kits-from-the-us-civil-war-reveal-historic-virus/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home