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What to know about the Bacille Calmette-Guérin (BCG) vaccine

Tuberculosis (TB) is an infectious disease that, if left untreated, can be deadly. It happens when you are infected with the bacteria Mycobacterium tuberculosis. The Bacille Calmette-Guérin (BCG) vaccination can assist people from contracting tuberculosis. However, health authorities in certain nations, such as the United States, do not suggest using the vaccination.

TB is a disease that mostly affects the lungs, although it can also harm other organs. While it is uncommon in the United States, it is a top cause of mortality in other regions of the world, according to the World Health Organization (WHO).

The Centers for Disease Control and Prevention (CDC) estimate that up to 13 million people in the United States have TB infection, despite the fact that the majority of cases occur in Asia and Africa and the global incidence is declining. Despite this, health authorities do not recommend the vaccination for all high-risk groups, including healthcare professionals and children in some countries.

The safety and efficacy of the BCG vaccination, as well as who should consider getting it, are discussed in this article.

What is tuberculosis (TB)?

What is TB?

TB is a contagious disease caused by an infection with the bacteria Mycobacterium tuberculosis (M.Tuberculosis). When a person with an active tuberculosis infection in their lungs coughs or speaks, it spreads via the air. Nearby people may then inhale the germ and develop the infection.

However, not everyone who contracts tuberculosis will get sick. Inactive or latent tuberculosis infection and active tuberculosis disease are the two types of tuberculosis infections.

When a person has latent tuberculosis, their immune system can fight the bacterium and prevent the disease from progressing. A person with a latent tuberculosis infection, on the other hand, will have no symptoms and will not be able to transfer the illness to others.

In other cases, however, the immune system is unable to prevent the germs from proliferating. When the tuberculosis bacteria is active, it is known as tuberculosis disease. The person causes symptoms such as fever, chest discomfort, and coughing up blood or mucus in these cases. People who have tuberculosis can pass the disease on to others.

BCG vaccine safety

After French doctors Albert Calmette and Camille Guerin developed and gave the BCG vaccination in1921, it has been accessible for more than 80 years.

The BCG vaccination employs an attenuated (weakened) TB strain called Mycobacterium bovis, which scientists isolated from cows. This strain is similar enough to M.Tuberculosis in humans to excite the immune system while causing no disease in healthy people.

According to research, the BCG vaccination appears to be safe. People may encounter side effects or bad responses to the immunization, like with any other vaccine. These may include the following:

  • soreness at the injection site
  • a small scar at the injection site
  • fever
  • headache
  • swollen glands

Allergic reactions, abscesses, bone inflammation, and widespread tuberculosis are all possible but unusual consequences.

Because the BCG vaccination is a live-attenuated vaccine, it is not recommended for immunocompromised or pregnant people, according to 2011 recommendations.

Vaccine effectiveness and duration

According to studies, the BCG vaccination is 70–80% effective against the most serious types of tuberculosis, such as TB meningitis. It is, however, less effective against TB that affects the lungs.

This conclusion is in line with recent findings indicating the vaccination has an effectiveness range of 0–80 percent Trusted Source and a 50 percent overall protective benefit against tuberculosis infection. Multiple factors, according to the researchers, might influence the vaccine’s efficacy, including variances in strains, administration method, and differences in people and environments.

The duration of protection from BCG vaccination is unknown, however some evidence suggests that protection lasts for ten years but may decrease with time. However, according to a 2018 research, the vaccination may provide modest protection for at least 20 years in individuals who had it as children.

Who should get it?

Due to the minimal risk of infection, inconsistent vaccination efficiency, and potential interference with the TB skin test, health authorities do not normally suggest administering the BCG vaccine in the United States.

Following a consultation with a TB expert and if people satisfy specified requirements, a healthcare practitioner may recommend a BCG vaccination in some cases. They can also talk to their local TB control program about the matter.

Children and healthcare professionals, according to the CDC, may be candidates for the BCG vaccination.

If a kid has tested negative for tuberculosis (TB) on a skin or blood test but has frequent contact with an adult who has the disease, they may be eligible for the vaccination. Similarly, healthcare workers who work in a setting where they deal with people who have disease should think about getting the vaccination.

Who should not get it?

In the United States, health professionals propose a tailored immunization strategy for high-risk groups rather than the BCG vaccine for the general public.

Due to probable consequences, the CDC also states that the vaccination is not recommended for immunosuppressed individuals, such as those with HIV, people who may become immunosuppressed, such as those awaiting organ transplantation, and pregnant women. People with a history of tuberculosis should avoid getting the vaccination since they are at a higher risk of having an adverse reaction to it.

How else can people prevent the spread of tuberculosis?

People can use additional TB preventive techniques in addition to the BCG vaccination. These can help prevent tuberculosis infection from becoming tuberculosis disease, as well as safeguard others in the community. This usually entails diagnostic testing to determine the type of tuberculosis infection and the administration of necessary drugs.

People can take the following precautions to help prevent the spread of tuberculosis:

  • completing their course of medications and taking the drugs exactly as their doctor prescribes
  • covering the mouth and nose when coughing and hand washing properly
  • using an effective mask or face covering, such as an N95 mask


The BCG vaccination is a preventative strategy that helps to keep tuberculosis from spreading. It stimulates the immune system and helps to prevent future infections by using a weakened strain of the M.Tuberculosis bacteria.

In the United States, health professionals typically advise against using the vaccination. Because of the minimal risk of infection, uneven efficacy, and potential interference with diagnostic testing. The vaccination, on the other hand, may be appropriate for people who are at high risk, such as children and healthcare professionals.