a decent historical view of 'vaccines, simpler times?
The Origin of Vaccines | AMS OpenMind
https://www.youtube.com/watch?v=E_PKQ_M7AtU
i am going to talk about this. i dont think it has ever been mentioned? i believe its called "cross species vaccination" and that is what happened with cow pox. cow pox was used as a vaccine against small pox. cow pox and small pox are so similar that the immune system recognizes them as the same?
but when you get just the least bit mutation to the flu virus and covid this doesnt work anymore?