Yes, there is a vaccine for tuberculosis. It’s called BCG (Bacille Calmette-Guérin), and it has been in use since 1921, making it one of the oldest vaccines still given today. Over 80% of countries worldwide include it in their routine childhood immunization programs. But BCG has a significant limitation: it protects young children well against the most dangerous forms of TB, yet its effectiveness against the common lung infection in adults is inconsistent. That gap is why TB still kills over a million people each year and why the search for a better vaccine continues.
What the BCG Vaccine Is
BCG is a live vaccine made from a weakened strain of a bacterium closely related to the one that causes human tuberculosis. Scientists originally took a virulent strain of cattle tuberculosis and weakened it through roughly 230 rounds of laboratory growth over more than a decade. The resulting organism is alive but too weak to cause disease in healthy people. When injected, it trains the immune system to recognize and fight tuberculosis bacteria without causing an actual infection.
The immune response BCG triggers is complex. It activates several branches of the immune system, prompting white blood cells to form organized clusters called granulomas that wall off TB bacteria. It also stimulates the production of antibodies and triggers a broad, nonspecific boost to immunity that appears to offer some protection against other infections as well, particularly in newborns and older adults.
How Well BCG Works
BCG’s strength is protecting infants and young children from the deadliest forms of TB, including TB meningitis (infection of the membranes around the brain) and disseminated TB, where the bacteria spread throughout the body. For these severe childhood forms, the vaccine is highly effective, which is why countries with significant TB burden vaccinate newborns as a matter of routine.
The problem is pulmonary TB, the lung infection that accounts for most TB cases and most transmission between people. BCG’s protection against pulmonary TB in adolescents and adults varies dramatically depending on geography, ranging in studies from near zero to around 80%. Several factors likely explain this inconsistency: exposure to related environmental bacteria that either mimic or interfere with the vaccine’s effects, genetic differences in both the vaccine strains and the populations receiving them, and the simple fact that the weakening process stripped out genetic regions the immune system may need to see for full protection. Researchers have identified 16 key genetic regions lost during that original weakening process compared to the human TB bacterium’s genome.
Protection also fades over time. BCG is most effective in the first 10 to 15 years after vaccination, and by adulthood, the protection it offered at birth has typically waned. This is the central challenge: TB is primarily a disease of adults, and the vaccine works best in children for a limited window.
Where BCG Is Used
More than 150 countries, about 80% of all nations, currently recommend BCG vaccination for all newborns. Every country in sub-Saharan Africa, Latin America, and East and South Asia follows universal vaccination guidelines. In these regions, TB remains common enough that the childhood protection BCG provides is well worth it.
The picture in Europe has been shifting. Between 2009 and 2019, thirteen countries changed their BCG policies, almost all of them European. Most moved from vaccinating every child to vaccinating only high-risk groups, such as children born to families from countries with high TB rates. Ireland stopped BCG vaccination entirely during that period due to supply shortages. Norway narrowed its recommendations for healthcare workers in 2018, while Belgium moved in the opposite direction and added mandatory BCG vaccination for healthcare professionals.
Why the U.S. Doesn’t Routinely Use BCG
The United States is one of the countries that does not include BCG in its routine vaccination schedule. TB rates in the U.S. are low enough that the benefit of mass vaccination doesn’t outweigh the drawbacks, and one drawback in particular drives the policy: BCG interferes with the tuberculin skin test, the standard screening tool used to detect TB infection.
After receiving BCG, a person may test positive on a skin test even if they’ve never been infected with TB. This makes it harder to identify people who actually have latent TB infection and need treatment. Blood-based TB tests are not affected by prior BCG vaccination, but the skin test remains widely used. In a country that relies on screening and targeted treatment rather than mass vaccination, a vaccine that muddies the screening results creates a real practical problem.
BCG is reserved in the U.S. for narrow circumstances. Children may be considered for vaccination if they have a negative TB test but are continuously exposed to an adult with TB that is untreated or resistant to standard drugs, and the child cannot be separated from that person or given preventive medication. Healthcare workers may be considered for BCG in settings where drug-resistant TB strains are circulating and standard infection control measures have failed. In both cases, the decision is made on an individual basis in consultation with a TB specialist.
Who Should Not Get BCG
Because BCG is a live vaccine containing weakened but living bacteria, it poses risks for people with compromised immune systems. Those with HIV, those receiving immunosuppressive medications (such as after an organ transplant or during chemotherapy), and those with other conditions that weaken immune function generally should not receive BCG. In a healthy person, the weakened bacteria are easily controlled. In someone whose immune system cannot mount a normal response, even the weakened strain can cause serious infection.
New Vaccines in Development
The limitations of BCG have driven one of the most active vaccine development efforts in global health. As of 2025, at least 18 TB vaccine candidates are in development, with six in advanced (phase 3) clinical trials. Several of these are being tested in South Africa, one of the countries hardest hit by TB.
The most closely watched candidate showed promising results in an earlier trial published in the New England Journal of Medicine, meeting the World Health Organization’s target for how effective a new TB vaccine should be. It is now being evaluated in a large trial across multiple countries in Africa and Asia. Unlike BCG, newer candidates aim to protect adolescents and adults against pulmonary TB, the form BCG handles poorly. Some are designed to be given as a booster to people who already received BCG as infants, extending protection into the years when TB risk is highest.
A vaccine that reliably prevents pulmonary TB in adults would fundamentally change the trajectory of the epidemic. TB remains the world’s deadliest infectious disease caused by a single pathogen, and the tools currently available, while they can cure the disease, have not been enough to bring case numbers down quickly. An effective adult vaccine is widely considered the missing piece.