Amazing Short on the History of Vaccine Effectiveness - includes Smallpox Story!

Very, very interesting - I didn't know any of the details really - and this is fully referenced to historical texts. Prepare to be amazed - especially at the Smallpox reality! Original vid link, please support maker: https://www.youtube.com/watch?v=kQivkd4uDOk&t=167s&ab_channel=RomanBystrianyk