Here is an Interesting article about the BCG vaccine. I’ve rewd about this a few weeks ago too. In the Uk, everyone got the vaccine as teenagers. We moved to the US just before our son was due to have it, but my husband and I and my daughter had that vaccine. It seems we would need a booster. I don’t think it has ever been a routine vaccine in the US.
BCG: Can a vaccine from 1921 save lives from Covid-19? https://www.bbc.co.uk/news/health-54465733