<prompt> BCG is the only widely used live bacterial vaccine. Which of the following statements is TRUE about BCG vaccination?Distilled water is used as diluent for BCG vaccineThe site for injection should be cleaned thoroughly with spiritMantoux test becomes positive after 48 hours of vaccinationWHO recommends Danish 1331 strain for vaccine production  <response>: The WHO has recommended the Danish 1331 strain for the production of BCG vaccine. Normal saline is recommended as a diluent for reconstitution of the vaccine, as distilled water may cause irritation. If alcohol is used to swab the skin, it must be allowed to evaporate before the vaccine is given. Normally the individual becomes Mantoux-positive after a period of 8 weeks has elapsed, but sometimes about 14 weeks are needed. Ref: Parks Textbook of Preventive and Social medicine, 19th edition, Page 160-161. 