Whether delayed BCG vaccination has any effect on the baby depends on the time of delayed vaccination. If the BCG vaccination is not given within 24h after birth, the vaccination can be made up directly within three months, and it will not have any effect in general. If it is more than three months, but not up to four years old, although you can make up the vaccination, but it will have an effect on the baby, because more than three months, it increases the chance of infection with tuberculosis mycobacteria, that is to say, may be infected with tuberculosis mycobacteria, so we should do the tuberculin test before the vaccination, and if the result is negative, you can make up the vaccination, and if the result is positive, you can’t make up the vaccination. BCG vaccination is mainly for the prevention of pediatric acute cornual tuberculosis and tuberculous meningitis, which have a high mortality rate. Parents are advised to vaccinate their babies on time in accordance with the immunization counting procedure on the premise that the babies are healthy, in order to promote healthy growth.