Smallpox vaccine provides protection for other viruses in the same family. In fact the original smallpox inoculation programs started when scientists noticed that milk maids who tended to get cow-pox from cows pretty much never died from smallpox and had much milder cases of it than other people.

Yes, but its an ‘old’ vaccine (because there wasn’t much funding/research put into it, because monkeypox was ‘contained’ in Africa, near where its endemic in the rodent population its native to).

The vaccine, which is actually just a smallpox vaccine, is a live virus vaccine, and therefore is genuinely somewhat risky. You will probably get moderately sick from getting it, and a few will get very sick from it.

As a result, its not a vaccine appropriate to give to everyone, but rather to do ‘barrier’ vaccination with. This includes ‘high risk groups’, but also, monkey pox is ‘slow’ enough you can get vaccinated after you think you’ve been exposed to it, just like with rabies and tetanus.

All of those reasons mean it is actually not that difficult to contain, provided actual resources are spent on tracking and maintaining the ‘barrier vaccinations’.