The BCG vaccine does exist, but it's an 90 year old live-virus vaccine with short-term side effects. Because it's a live-virus "natural" vaccine, it can't be used on people who are immunocompromised or have HIV. There's work on more modern vaccines.[1] No big successes yet.

The safety record of the BCG vaccine, in terms of permanent harm, is pretty good. But a normal side effect is "The usual expected reaction to BCG vaccination is redness and/or a small lump at the injection site, followed by a small ulcer (open sore) a few weeks later (usually less than 1 cm in diameter). The ulcer may last from a few weeks to months before healing to a small flat scar."[2] Mass vaccination will have parents screaming "my perfect baby has an open sore from the vaccine" on Instagram, with pictures.

The classic live-virus smallpox vaccine has similar side effects, by the way, plus a death rate of 1-2 per million.

Huge political problem. Remember all the screaming about the COVID vaccines, which are pure RNA, can't replicate, and have fewer side effects.

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC3349743/#s6

[2] https://www.rch.org.au/uploadedFiles/Main/Content/immunisati...