This study aims to see if the BCG vaccine, a shot used to protect against tuberculosis (TB), can help adults traveling to places with lots of TB. TB is a serious lung disease. The BCG vaccine is common in some parts of the world but not approved in the US, so it's considered experimental here. The study will give either the BCG vaccine or a placebo (a fake shot) to about 2000 people and see how many get TB. Participants will be chosen randomly, like flipping a coin.

• The study will need 4 to 6 visits, including check-ups and vaccinations.
• Participants must be healthy adults aged 18-65 who will travel to places with high TB rates for at least 4 weeks.
• Participants cannot have a history of TB, certain health issues, or recent live vaccines.

Participants will answer questions, have check-ups, and get blood tests. The study will check if they are at risk of TB during their travels and if the vaccine works. If you join, you must follow the study's rules and attend all visits. This research might help protect people from TB in the future.