Latent Mycobacterium tuberculosis infection in a 16-year-old child is not serious. Mycobacterium tuberculosis latent infection means that the organism is infected with Mycobacterium tuberculosis, but no clinical tuberculosis has occurred, and there is no clinical bacteriologic or imaging evidence of active tuberculosis. A person with latent tuberculosis infection has no signs and symptoms associated with tuberculosis, is not contagious, and can live and study as a normal person. Although people with latent tuberculosis infection do not develop active tuberculosis, some of these patients may develop active tuberculosis when their body resistance declines. It is recommended that people with latent tuberculosis infection strengthen physical exercise, regular work and rest, balanced nutrition, in order to improve the body’s immunity. You can also apply anti-tuberculosis drugs (rifampicin, etc.) as prescribed by the doctor for preventive treatment. It is recommended that children be vaccinated with BCG vaccine according to the immunization program, which can prevent them from being infected by tuberculosis bacteria. Avoiding crowded places, wearing masks when going out, refraining from spitting, and washing hands promptly after returning home can also reduce the infection rate of Mycobacterium tuberculosis.