Yes, there is a tuberculosis vaccine, but it works differently than most vaccines you know

The tuberculosis vaccine is called BCG (Bacille Calmette-Guérin). It is a live weakened form of the bacterium that causes TB. Unlike vaccines for measles or polio, BCG does not prevent infection entirely — it reduces the chance that someone who catches TB will develop the active disease, especially the severe forms that spread through the lungs.

BCG is given as a single injection, usually into the upper arm. It leaves a small scar in most people who receive it. The vaccine works best when given to infants and young children, and protection tends to fade over decades, which is why booster shots are sometimes used in high-risk settings.

The United States does not routinely give BCG to the general population. Most other countries do. This difference matters if you are traveling, moving, or trying to understand why your medical records show a BCG scar but you do not remember getting the shot.

Key Takeaways

  • BCG is a live weakened vaccine that reduces the risk of active TB disease, particularly severe forms, but does not prevent infection.
  • The United States does not include BCG in routine childhood vaccinations, though most other countries do.
  • BCG is given as a single injection and typically leaves a visible scar on the upper arm.
  • Healthcare workers and people with HIV who have been exposed to TB may receive BCG in certain circumstances, even in the United States.
  • Protection from BCG decreases over time, so booster doses may be recommended for people in high-risk settings.

Why the United States does not use BCG routinely

The U.S. stopped recommending BCG for all children in the 1980s because TB rates were already very low and falling. The decision was based on the idea that preventing TB infection through testing, treatment, and isolation was more effective than vaccinating a population with low disease risk.

BCG also complicates TB screening. After you receive BCG, a tuberculin skin test (the traditional TB test) may show a positive result even if you have never been exposed to TB. This makes it harder to tell who actually has TB infection and who just has vaccine immunity. Blood tests like the IGRA (interferon-gamma release assay) can distinguish between the two, but they cost more and are not always available.

The U.S. approach assumes that TB cases will be caught through symptoms and testing rather than prevented by vaccination. This works well in a country with low TB rates, good healthcare access, and reliable treatment. In countries with higher TB rates or less reliable healthcare systems, BCG vaccination of infants remains standard practice.

Who does receive BCG in the United States

BCG is not part of the routine childhood vaccine schedule in the U.S., but certain groups may receive it. Healthcare workers who have been exposed to TB and cannot take preventive medications may be offered BCG. People with HIV who have been exposed to TB and have a very low CD4 count may also be candidates.

The decision to give BCG to these groups is made on a case-by-case basis by infectious disease specialists or occupational health doctors. It is not a standard recommendation, and it requires careful consideration of the person's TB exposure risk, their ability to take other preventive treatments, and the likelihood that BCG will provide meaningful protection.

How BCG protection works and how long it lasts

BCG works by training the immune system to recognize and fight the TB bacterium. When someone vaccinated with BCG later encounters the real TB bacterium, their immune system can respond faster and more effectively. This does not always prevent infection, but it often prevents the infection from progressing to active disease.

BCG is most protective against severe TB in young children — particularly TB meningitis and disseminated TB, which are life-threatening forms. Protection against TB in the lungs (the most common form in adults) is less consistent, ranging from about 50 to 80 percent depending on the study and the population.

Protection from BCG decreases over time. Studies show that after 10 to 15 years, the vaccine's effectiveness drops noticeably. After 20 years or more, protection may be minimal. This is why some countries give booster doses to adolescents or adults in high-risk occupations, though the benefit of boosters is debated among TB experts.

BCG and TB skin tests: why the scar matters

If you have a BCG scar, a tuberculin skin test (Mantoux test) may come back positive even if you have never been exposed to TB. This false positive happens because the skin test cannot distinguish between immunity from vaccination and immunity from actual TB infection.

Blood-based TB tests, called IGRAs, are more specific. They can tell the difference between BCG vaccination and real TB infection in most cases. If you have a BCG scar and need TB screening — for a job, school, or immigration — ask your doctor whether an IGRA would be appropriate. It may save you from unnecessary further testing or treatment.

If you received BCG as a child in another country and now live in the U.S., keep a record of when and where you were vaccinated. This information helps doctors interpret your TB test results correctly.

BCG side effects and safety

BCG is a live vaccine, which means it contains weakened but living bacteria. In healthy people, serious side effects are rare. The most common reactions are mild: redness, swelling, or a small ulcer at the injection site that heals within weeks and leaves the characteristic scar.

People with severely weakened immune systems — including those with untreated HIV or certain genetic immune disorders — should not receive BCG because the weakened bacteria can cause serious infection. Pregnant people are also not given BCG, though it is safe to give to infants born to vaccinated mothers.

BCG has been used safely in infants worldwide for nearly a century. Serious complications are documented but extremely rare. The vaccine is on the World Health Organization's list of essential medicines.

BCG in countries outside the United States

Most countries outside the U.S. include BCG in their routine infant vaccination schedule. It is typically given at birth or within the first few weeks of life. In countries with higher TB rates, this vaccination prevents thousands of cases of severe TB in children each year.

If you were born outside the U.S. and have a BCG scar, you almost certainly received the vaccine as an infant. If you are planning to move to another country or are sponsoring family members for immigration, be aware that some countries require BCG vaccination or proof of previous vaccination for certain visa categories or work permits.

Frequently Asked Questions

Can I get BCG if I live in the United States?

BCG is not routinely given in the U.S., but it may be available through your doctor or occupational health clinic if you have a specific exposure risk and cannot take other TB preventive medications. You would need to discuss this with an infectious disease specialist or your occupational health provider.

Does BCG protect against all types of TB?

No. BCG is most protective against severe TB in children, particularly TB meningitis. Protection against TB in the lungs (pulmonary TB) is less reliable and varies widely. It does not prevent TB infection, only the progression to active disease in some cases.

If I have a BCG scar, does that mean I am immune to TB?

A BCG scar means you were vaccinated, but it does not may provide immunity. Protection decreases over time and varies between individuals. You can still catch TB even with a BCG scar, though severe disease is less likely. A positive TB skin test in someone with a BCG scar does not automatically mean TB infection.

Why did the U.S. stop using BCG if other countries still use it?

The U.S. has very low TB rates and good healthcare access, so preventing TB through testing and treatment was considered more effective than vaccination. In countries with higher TB rates, BCG vaccination of infants remains the standard because it prevents many cases of severe TB in children.

Will I need a booster shot if I received BCG as a child?

Booster shots are not standard in most countries, though some high-risk settings offer them. Protection from childhood BCG decreases over decades. If you work in healthcare or another high-risk setting and were vaccinated long ago, talk to your occupational health provider about whether a booster or other TB preventive measures make sense for you.