Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis and primarily affects the lungs. The main preventative measure against it is the Bacillus Calmette-Guérin (BCG) vaccine, which has been in use for over a century. The BCG vaccine is highly effective at protecting infants and young children from severe forms of TB, such as miliary TB and TB meningitis. However, its availability and administration policies vary significantly worldwide, depending almost entirely on the geographic prevalence of the disease.
Global Deployment of the BCG Vaccine
The BCG vaccine is widely used globally, with over 80% of neonates and infants receiving it in countries where it is part of the national childhood immunization program. This widespread use is primarily concentrated in regions with high TB incidence rates, which are typically defined as having 40 or more cases per 100,000 people annually. More than 150 countries currently recommend universal BCG vaccination for infants to reduce childhood morbidity and mortality associated with the disease. Regions like Southeast Asia, Sub-Saharan Africa, and parts of the Western Pacific consider universal BCG vaccination a standard public health strategy. In these high-burden areas, infants are typically vaccinated shortly after birth, often before leaving the hospital.
Conversely, approximately two dozen countries, including the United States and many Western European nations, have either discontinued routine use or never adopted it due to low TB incidence. The protective efficacy of the BCG vaccine against adult pulmonary TB is considered variable, which is one reason for its discontinuation in low-prevalence countries. In these nations, the public health strategy shifts toward early detection and treatment of latent or active TB. The vaccine’s use can also complicate the interpretation of the standard Tuberculin Skin Test (TST), making widespread screening less reliable.
Obtaining the Vaccine in Low-Incidence Countries
For individuals residing in countries that do not have a routine BCG program, such as the U.S., Canada, or the UK, obtaining the vaccine requires specialized access and is not available through a standard pediatrician or family doctor’s office. Access is highly selective and often reserved for specific high-risk groups. The vaccine is typically administered at specialized travel health clinics, which cater to individuals planning extended stays in high-prevalence areas, particularly young children. Some occupational health departments also provide the vaccine for healthcare workers or laboratory personnel with a high risk of exposure to drug-resistant TB strains.
Public health departments in some large metropolitan areas may also offer selective BCG vaccination programs. These programs often focus on infants and children within communities that have historically higher TB rates, such as certain immigrant or indigenous populations. Access often requires a private consultation, and the cost of the vaccine and administration may be paid for out-of-pocket, as it is not covered by routine national health insurance for the general population.
Medical Criteria for Receiving Immunization
Strict medical criteria must be met before administration. The most fundamental requirement is that the recipient must not have a pre-existing Mycobacterium tuberculosis infection. This is typically confirmed through a screening process using either a Tuberculin Skin Test (TST) or an Interferon-Gamma Release Assay (IGRA) blood test. A patient must have a negative TST result, usually defined as an induration of less than 5 millimeters, before the BCG vaccine can be given. If a person tests positive, they are considered to have a latent TB infection, and the vaccine is not recommended. High-risk individuals generally considered eligible include infants or children who are continually exposed to untreated or ineffectively treated TB patients. The vaccine is also contraindicated for several medical conditions that compromise the immune system:
- Individuals with HIV infection.
- Those with leukemia or lymphoma.
- Patients undergoing immunosuppressive therapy.
- Pregnant individuals (the vaccine is generally not recommended due to insufficient safety evidence).
If a child is older than six months and missed vaccination at birth, a pre-vaccine TST is required to detect any prior infection before immunization.