Tuberculosis: The Disease & Vaccines
The tuberculosis (TB) vaccine is rarely used in the United States. It is only recommended for children living with someone who is actively infected with TB who either (1) cannot take antibiotics to treat the infection or (2) is infected with a strain of TB that is highly resistant to all antibiotics. Decisions regarding this vaccine are typically made in consultation with a local TB control program. The TB vaccine is given as a single shot.
In most other countries, the vaccine for tuberculosis, known as the BCG vaccine, is used more commonly because of the frequency of tuberculosis.
The disease
The impact of tuberculosis
Tuberculosis kills more people in the world than any other infection. Each year about 10 million people are infected with TB and about 1.8 million die. Cases of TB occur in the United States each year, but most are diagnosed in people not born in the U.S. In 2018, less than 10,000 cases of TB and fewer than 500 deaths were caused by TB.
What is tuberculosis?
Tuberculosis (TB) is caused by a bacterium, Mycobacterium tuberculosis. The infection primarily attacks the lungs. The bacterium is so destructive that it is common to cough up both mucus and blood. Those less than 5 years old are susceptible to a severe, often fatal, form of TB (called "miliary" TB) that spreads to many parts of the body, including the lining of the brain (meninges).
Extremely contagious, TB is spread through the simple act of sneezing, talking and coughing. Many people who are infected don't get sick right away; rather, the bacteria remain dormant, reactivating years, even decades, later. That's when lung disease and the characteristic cough begin.
A tuberculin skin test (TST; also sometimes called a PPD test, which stands for “purified protein derivative”) and chest X-ray are the best ways to tell if someone is infected with TB. A blood test can be used in older children and adults.
Is the incidence of TB in the United States increasing?
The incidence of tuberculosis had been steadily increasing in the United States since the 1980s coincident with the HIV epidemic. However since 1993, a slow decline in the number of cases has occurred likely due to better control of HIV with the use of anti-retroviral drugs. Unfortunately, the rate of decline is so slow that predictions suggest tuberculosis will not be eliminated from the United States during this century.
Tuberculosis (TB) Q&A
TB Special Topics Q&A
The vaccine
How is the tuberculosis vaccine made?
Known as BCG, the TB vaccine has been around since the early 1920s. It is made by weakening a strain of bacteria similar to tuberculosis that was first isolated in cows. This strain of bacteria, called Mycobacterium bovis, is similar enough to the human strain (Mycobacterium tuberculosis) that vaccination with the bovine strain protects against disease caused by the human strain.
Does the tuberculosis vaccine have side effects?
Soreness at the site of the injection is common. About 3 of every 10,000 people immunized with the tuberculosis vaccine develop painful swelling under the arm.
Who should get the tuberculosis vaccine?
The tuberculosis vaccine is recommended only for those children living with someone with TB who either cannot take the antibiotics required to treat the infection or who is infected with a strain that is highly resistant to all antibiotics. Ultimately, only a small number of people in the United States fall into these categories.
Other questions you might have
Since TB is increasing in the United States, why isn't the vaccine recommended for everyone at risk of catching the disease?
The TB vaccine is good at protecting against the severe form of disease found in young children (called "miliary" TB), but it is not as good at protecting against the lung infection commonly found in adolescents and adults. Because miliary TB is very uncommon in the United States, we do not routinely use the TB vaccine. The United States is one of only two countries that have never routinely used the TB vaccine (The Netherlands is the other).
If we are not routinely using the tuberculosis vaccine, what are we doing to stop the spread of tuberculosis in the United States?
The United States does two things to stop the spread of TB. First, people who are actively or silently infected with TB are identified by performing regular skin tests (referred to as either TST or PPD). Second, once identified, people with TB are treated with one or more antibiotics that are effective against the bacteria: specifically, isoniazid (or INH), rifampin, ethambutal or pyrazinamide.
Relative risks and benefits
Do the benefits of the tuberculosis vaccine outweigh its risks?
The tuberculosis vaccine is not highly effective at preventing lung infections caused by the tuberculosis bacteria. For this reason, the vaccine is only recommended for a small subset of those in contact with someone infected with tuberculosis ─ specifically someone in constant contact with a person infected with TB who either refuses to take antibiotics or is infected with a strain that is resistant to all antibiotics. On the other hand, the tuberculosis vaccine has no serious side effects. Therefore, in the small subset of people who should use the vaccine, the benefits clearly outweigh the risks.
Disease risks
- Coughing up blood and mucus
- Antibiotics don’t always work
- Can lead to miliary TB, particularly in children, spreading to other parts of the body including the meninges
- Disease can be fatal
Vaccine risks
- Pain at the injection site
- Painful, swelling under the arm (3 in 10,000 people)
- May not protect against more common type of tuberculosis
References
Plotkin SA, Orenstein W, Offit PA and Edwards KM. Tuberculosis vaccines in Vaccines, 7th Edition, 2018, 1095-1113.
Centers for Disease Control and Prevention. Data and Statistics. September 6, 2019.
Schmit KM, Wansaula Z, Pratt R, Price SF, Langer AJ. Tuberculosis-United States, 2016. MMWR Morb Mortal Wkly Rep 2017; 66:289-296.
Reviewed by Paul A. Offit, MD, on May 11, 2020