@kpger Interesting! My ID doctor had me tested also and at my appointment last week, he told me the results showed IGG subclass 2 was low and my IMM was a little low as well. He said that neither was of great concern but referred me to a hematologist for further follow up. Other than MAC, I have always been healthy. I haven't had the flu in over 10 years, I get a cold every few years but it is never a big deal, never got COVID. I do not take any vaccines because I don't want to fix what's not broken. However, it will be interesting to follow up on this to see if there is any connection with the MAC .