If you are from a different country and have a scar on your upper arm, it is likely that you are one of millions of people who have received the BCG vaccine. Despite its widespread use, many people feel confused about what the BCG vaccine is and why it is done. Read on to learn more about this important tuberculosis vaccine.
BCG Vaccine – What Is It?
The BCG vaccine is a special vaccine that is used to protect people against tuberculosis. Tuberculosis is a contagious disease that is present in many countries around the world and the BCG vaccine shows protective effects of 60% or more against tuberculosis. 1 The protection offered by the BCG vaccine can last several decades, depending on the person. The BCG vaccine is also thought to offer some protection against meningitis and be beneficial in people with bladder cancer. Research is also being done to investigate if the BCG vaccine offers any protective effect against COVID-19.
BCG Vaccine – Who Gets The Vaccine
The BCG vaccine is one of the most commonly used vaccines throughout the world. In particular, it is widely used in countries in which tuberculosis is common as a way to protect people against tuberculosis.
There are several groups of people for whom the BCG vaccine should be considered (please consult the CDC for current guidelines):2
- Children. The BCG vaccine can be considered in children who have a negative TB skin test and are around untreated adults with TB or adults with TB-resistant strains.
- Healthcare Workers. BCG immunization should be considered in healthcare workers who are at a high-risk for exposure to TB-resistant strains.
People in the United States who are from foreign countries will frequently have received a BCG vaccination. The BCG vaccine is not generally recommended as part of the routine vaccination series for children born in the United States because of the low incidence of tuberculosis and questions about how well it works in the setting of active tuberculosis in the lungs. BCG vaccination should not be given during pregnancy or to people who have a compromised immune system.
BCG Vaccine History
The “BCG” in BCG vaccine stands for Bacillus Calmette-Guérin. Used for almost a century, the BCG vaccine, at a wholesale price of under $1.50 per dose, is considered an essential medication by the WHO and is given to approximately 100 million children per year.3
BCG Vaccine Administration
The BCG vaccine is given to people in countries with a high prevalence of tuberculosis. Generally, one dose of the BCG vaccine is given to newborns when possible. In children and adults who have missed the routine vaccination, the BCG vaccine can also be administered. Prior to administering the BCG vaccine, a TB skin test is usually done as someone who has a positive TB skin test should not receive the BCG vaccine. The BCG vaccine should also be avoided in pregnant women.
The BCG vaccine is administered as an injection in a shoulder muscle known as the deltoid. It is injected intradermally. There are very few side effects experienced after being vaccinated with BCG if it was administered correctly. Like most vaccines, the most common side effect is pain or redness at the site at which the BCG vaccine was administered. Rarely, more significant infections can occur at the infection site. Most people who have received the BCG vaccine will have a noticeable, raised circular scar at the site of the vaccination.
People with weak immune systems should not receive the BCG vaccine. In these situations, administration of this tuberculosis vaccine can cause life-threatening illness and infections.
BCG Vaccine & TB Testing
While the BCG vaccine has protective effects against tuberculosis, this vaccine also has its downsides. Aside from the pain associated with receiving the vaccine and subsequent scarring, the BCG vaccine affects any subsequent testing performed when one is being screened for tuberculosis.
More specifically, people who have received the BCG vaccine will test positive falsely on the common form of the TB screening exam, the TB skin test. The TB skin test is considered positive when one has a large, raised bump after the test and people who have had the BCG vaccine will almost always have a positive test due to cross-reactivity between the BCG vaccine and the components of the TB skin test injection ingredients. Because the follow up test to a positive TB skin test is a chest x-ray, people who have received a BCG vaccine in the past are exposed to radiation from a chest radiograph every time they needed to be screened for tuberculosis.
In recent years, other ways to screen for tuberculosis have made it easier to differentiate whether people who have received the BCG vaccine been actually exposed to tuberculosis or not. One lab testing innovation known as the QuantiFERON-Gold TB blood test has become increasingly relevant in testing people who have received the BCG vaccine for a tuberculosis infection. The QuantiFERON TB blood test is valuable for people who have had the BCG vaccine because it can accurately differentiate between whether someone has been exposed to a tuberculosis infection or not after receiving the BCG vaccine.
Future of the BCG Vaccine
The BCG vaccine has been important in preventatively protecting people at a high-risk for getting tuberculosis from getting it in spite of the inconvenience it causes. Because there are only a few suppliers of the BCG vaccine, there is always a risk that there will be shortages if one of the BCG vaccine facilities is impaired as is what happened with one of the manufacturers – Sanofi Pasteur – in 2011.