BCG vaccination is beneficial for the healthy development of children and has a considerable role in the prevention of tuberculosis, especially serious types of tuberculosis that may endanger children’s lives, such as tuberculous meningitis and cornual tuberculosis. Studies by the World Health Organization (WHO) have confirmed that the average effectiveness of BCG vaccination in preventing tuberculous meningitis and disseminated tuberculosis is 86%; 65% in preventing tuberculosis-related deaths, 64% in preventing deaths from tuberculous meningitis, and 78% in preventing deaths from disseminated tuberculosis. Over the years, thousands of lives have been saved through BCG vaccination. So how is BCG vaccination for babies considered a failure? What should I do if it is not successful? How do you recognize a vaccination failure? Nowadays, the success rate of BCG vaccination is about 95%. Most children will have local reactions 3-4 weeks or 1-2 weeks after BCG vaccination, through a process of redness, swelling, infiltration, pustule formation, breaking and crusting, and usually the crusts will come off and local scars will be formed in about 3 months. This is a normal reaction process after BCG vaccination and is a sign of effective vaccination. If this does not occur, it should be considered that the vaccination has not been successful, and this is a situation that needs to be replanted. Therefore, it is generally necessary to look at the post-vaccination marks to see whether the BCG vaccination has been successful or not. What if BCG vaccination is unsuccessful in newborns? The success rate of BCG vaccination cannot be 100%. Many factors can affect the effectiveness of the vaccination, such as the individual differences of the newborn, the level of immune response, the health condition at the time of vaccination and the vaccination technique. It is also possible that the BCG vaccine may not be kept cold at all times during production, transportation and storage, resulting in a decrease in BCG potency and unsuccessful vaccination. Even if the BCG vaccination is unsuccessful, parents should not panic. If they are really unsure, they can go to the hospital for an examination and can do a tuberculin test (PPD skin test) to see if the child is successfully vaccinated and to see if the body has antibodies or not. If the test determines that no antibodies have formed, the vaccination can be repeated.