I don’t know if he mentions small pox. That was just an example of a really old disease. Not to mention it being the most successful vaccine campaign literally ever, since it actually led to the eradication of the disease.

IIRC, the current hypothesis was that modern HIV originated in Central Africa, where bush meat was commonly consumed. A version of a simian immunodeficiency virus managed to infect a human, probably through blood contact through wounds or… other means. This new HIV began to spread in Africa, where missionaries eventually picked up the disease. These missionaries then spread it all over the world. It was estimated that HIV first got to the US in the 1910s or 20s. It wasn’t until the 70s that the gov gave any shits, because it was considered the “gay disease” and the such. When a bunch of straight white people started getting it, then they cared a bit.

The reason HIV is such an issue to this day, and why its so stigmatized, can be traced to the likes of Regan and his contemporaries who went out of their way to make it even worse of a situation than it already was. They purposely avoided doing anything about it until it was too late.