Tuberculosis (TB) is caused by a bacterium, Mycobacterium tuberculosis (Mtb). It is a curable and preventable disease that most often affects the lungs. TB is transmitted from person to person, by people with pulmonary (lung) TB who release Mtb into the air through coughing, sneezing or spitting. A person needs to inhale only a few of these germs to become infected. About one-third of the world's population is estimated to be infected by Mtb, but are not (yet) ill with disease and cannot transmit the disease. People infected with TB bacteria have a lifetime risk of falling ill with TB of 10%, as opposed to persons with compromised immune systems, such as people living with HIV, malnutrition or diabetes, or people who use tobacco, who have a much higher risk of falling ill. When a person develops active TB (disease), the symptoms (cough, fever, night sweats, weight loss etc.) may be mild for many months. This can lead to delays in seeking care, and results in transmission of the bacteria to others. People ill with TB can infect up to 10-15 other people through close contact over the course of a year. Without proper treatment up to two thirds of people ill with TB will die.
Live Bacille Calmette-Guérin (BCG) vaccine, derived from the TB vaccine developed in 1921 remains the only vaccine against TB. Unfortunately, it is only partially effective: it provides some protection against severe forms of pediatric non-pulmonary (non-lung) TB, such as TB meningitis, but is unreliable against adult pulmonary (lung) TB, which accounts for most of the TB disease burden worldwide.
WHO continues to recommend the vaccination of neonates with BCG, due to its protective effect in infants and young children. However, children infected with HIV through vertical transmission from their HIV-infected mother are at risk of developing severe vaccine-related disease (“BCGosis”). Therefore, children known to be HIV infected should not be vaccinated with BCG.
There is therefore an urgent need for a new, safe and effective vaccine that prevents all forms of TB, including drug-resistant strains, in all age groups and in people with HIV. TB vaccine development is a very active field of research, with a number of vaccine candidates already in clinical evaluation in humans.
WHO position papers
English and French version (January 2004)
Revised BCG vaccination guidelines for infants at risk for HIV infection (2007)
- Full list of WHO position papers and accompanying documents
- Immunization schedules
Disease burden and surveillance
Guidelines for National Regulatory Authorities
Requirements for dried BCG vaccines 1985 revision
Requirements for dried BCG vaccines 1987 amendment
Immunological basis of vaccination
Links to other WHO tuberculosis related materials
Related partner links
Last updated: 24 January 2014