Thanks for using ask a doctor s service from doctor spring .i will try to answer your query at the best possible. I would suggest you to hold on to the diet plans for a week till you are completely done with the TB vaccine. BCG vaccine also known as Bacille Calmette Guerin Vaccine is given for tuberculosis. It consists of a live attenuated virus of the Mycobacterium Bovis introduced into the body. The dosage given is about 0.10 ml in the deltoid region of the arm and followed with post vaccine test after 2-3 months. When you go on a diet your immunity is low making it more susceptible for infections to develop following a BCG vaccination. After the vaccine you may have chances of developing malaise, fever with chills, nausea, vomiting. The T cells are produced immediately in response to the virus introduced that protects the body from the infections. So it would ideal if you give a week after the vaccination to resume your diet. Hope this helps.