Safety, Immunogenicity, and Efficacy of Therapeutic Mycobacterium Bovis BCG (BOOST)

The purpose of this study is to find out if the Mycobacterium bovis Bacillus Calmette Guerin (BCG) vaccine can be used safely to treat Mycobacterium avium complex (MAC) lung disease. Researchers will compare responses from patients with MAC lung disease after receiving an injection of BCG or placebo (a look-alike substance that contains no drug) Participants in the study: * Receive a BCG or placebo injection at UVA study center on Day 0 * Come to UVA study center on Day 60 * Come to UVA study center at the end of the study * Answer surveys and questionnaires about how you are doing * Have blood drawn 3 times, on injection day, day 60, and at end of study * Give the study team personal and demographic information * Discuss any new symptoms with the study team * Provide monthly sputum samples per usual care