Dr. Lucky Tran 
Vaccines are one of the most important inventions humans have ever made. Period.
Carl (He/Him)@luckytran TB? The only TB vaccine I'm familiar with, BCG, is either totally or nearly useless. Last time I looked (years ago, admittedly), it worked only in Europe and not very well there. Inexplicably only working in one region is something it shares with, say, acupuncture (only found to have good effects in China, where you can't publish negative results on acupuncture, literally).
Josh G@nitpicking @luckytran I would be interested in your sources there @nitpicking . From a quick search myself, it looks like you're right that BCG is the only TB vaccine, but I can't quite see where the "nearly useless" comes from. According to a few places, but probably most credibly the CDC (https://www.cdc.gov/tb/vaccines/index.html), the reason it's not used in the USA is because there isn't much TB in the USA.
I can see from the WHO (https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/norms-and-standards/vaccines-quality/bcg) that it seems to prevent "disseminated TB" in people who are infected, which is the "more severe form of TB", but doesn't prevent infection.
I can't see anywhere that says it only works in Europe, though.
@Josh_Gallagher @luckytran I don't currently have access to scholarly pubs (that are paywalled), but here's a link I found: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(95)92348-9/fulltext
The way I was told (by a doctor at a convention) is that results vary across geography, and no one is sure why. It never seems to have *much* of an effect. I'm not a medical researcher. What I wrote is pretty consistent with what Wikipedia says, FWIW.