Yes, there is a TB vaccine, but most people in the United States do not receive it

The vaccine is called BCG (Bacille Calmette-Guérin). It has been used worldwide for nearly 100 years and is given to infants in most countries outside North America and Western Europe. In the United States, the BCG vaccine is not part of the routine childhood schedule. Instead, it is offered only to people at high risk of tuberculosis exposure — mainly healthcare workers, people living with someone who has active TB, or people planning to move to a country where TB is common.

The reason for this difference comes down to how well the vaccine works and how common TB is. In countries where tuberculosis is widespread, the benefits of vaccinating everyone outweigh the drawbacks. In the United States, where TB is rare, doctors focus on testing and treating people who are actually exposed rather than vaccinating large populations.

Key Takeaways

  • The BCG vaccine prevents severe TB disease in children and is used in most countries, but not routinely in the United States.
  • BCG works best at preventing TB meningitis and disseminated TB in young children, but is less effective at stopping the most common form of TB in adults.
  • In the United States, BCG is offered mainly to healthcare workers, close contacts of people with active TB, and people moving to high-TB countries.
  • After BCG vaccination, a TB skin test will show a positive result for years, which can complicate future TB screening.

How the BCG vaccine works

BCG is a live attenuated vaccine, meaning it contains a weakened form of the bacterium that causes TB. When injected, it trains your immune system to recognize and fight TB without causing the disease itself. The vaccine is given as a single shot, usually in the upper arm, and leaves a small scar in most people who receive it.

The vaccine is most effective at preventing severe TB in infants and young children — particularly TB meningitis (infection of the membranes around the brain) and disseminated TB (TB that spreads throughout the body). These are the most dangerous forms of TB in young children. In adults, BCG is less effective at preventing the most common form of TB, which affects the lungs.

Why the United States does not routinely vaccinate against TB

The United States stopped recommending BCG for all children in the 1980s for two main reasons. First, TB rates in the country are low enough that the risk of exposure for most people is small. Second, the vaccine creates a permanent change in TB skin tests — a standard screening tool used in healthcare and employment.

After BCG vaccination, a TB skin test will show a positive result for years, even if you have never been exposed to TB. This makes it harder to tell whether a positive test means you have been infected or simply received the vaccine. In a country where TB is rare, this trade-off does not make sense for the general population. Instead, the U.S. approach focuses on identifying and treating people who are actually infected.

Who should consider the BCG vaccine in the United States

The Centers for Disease Control and Prevention (CDC) recommends discussing BCG vaccination with a doctor if you fall into one of these groups: healthcare workers with ongoing exposure to TB patients, people who will be living with someone who has active TB disease, or people planning to move to or spend significant time in a country where TB is common.

A doctor will review your TB test results and medical history before recommending BCG. If you have already tested positive on a TB skin test or blood test, you will not receive the vaccine. The vaccine is also not given to people with weakened immune systems, including those with HIV or those taking certain medications that suppress immunity.

What happens after BCG vaccination

After receiving BCG, you will develop immunity to TB within two to three weeks. The vaccine's protection is strongest in the first 10 to 15 years and gradually decreases over time. Some protection may last a lifetime, but it is not may provide.

The most important side effect is the change to TB skin testing. Any TB skin test you receive after vaccination will likely show a positive result, even if you have never been infected with TB. If you need TB screening in the future — for a job, healthcare setting, or because of a known exposure — you will need to use a blood test instead, such as an interferon-gamma release assay (IGRA). Make sure any healthcare provider knows you received BCG so they use the correct test.

BCG vaccination outside the United States

In most countries, BCG is given to all infants as part of the routine vaccination schedule. The World Health Organization recommends it for countries where TB is a significant public health problem. If you were born outside the United States and received BCG as a child, you likely have a small scar on your upper arm and will have a positive TB skin test for life.

If you were vaccinated with BCG abroad and later move to or work in the United States, inform your doctor about the vaccination. This is especially important if you ever need TB screening, since your healthcare provider will need to use a blood test rather than a skin test to determine whether you have been infected with TB.

Frequently Asked Questions

Can I get BCG if I have already tested positive for TB?

No. If you have tested positive on a TB skin test or blood test, you should not receive BCG. A positive test means you have been infected with TB, and the vaccine is not effective in people who are already infected. Your doctor will discuss treatment options instead.

Does BCG protect me completely from tuberculosis?

No. BCG provides strong protection against severe TB in children but is less reliable in adults. Even vaccinated people can develop TB if exposed to the bacteria. This is why people at high risk still need regular TB screening and should take precautions to avoid exposure.

If I received BCG as a child, do I need a booster?

No. The CDC does not recommend booster doses of BCG. Protection from the original vaccination may last a lifetime, though it weakens over time. If you were vaccinated years ago and are now at high risk of TB exposure, talk to your doctor about whether additional screening or preventive treatment is needed.

Why does BCG make TB skin tests positive?

BCG contains a weakened form of the TB bacterium. Your immune system responds to the vaccine by producing antibodies and immune cells that react to TB bacteria. When a TB skin test is performed, it cannot distinguish between a reaction to the vaccine and a reaction to actual TB infection, so the test appears positive.

What should I do if I am traveling to a country with high TB rates?

Talk to your doctor at least four to six weeks before your trip. They can review your TB test results and vaccination history to determine whether BCG or other preventive measures are appropriate for you. If you will be working in healthcare or spending extended time in high-risk settings, vaccination may be recommended.