Overview of Bacillus Calmette Guerin
The Bacillus Calmette-Guérin (BCG) vaccine is a type of vaccine that’s given to protect against tuberculosis, a serious lung disease, and other similar infections. It uses a weakened form of a bacteria called Mycobacterium bovis. The vaccine was first developed by two scientists, Calmette and Guérin, and was given to humans for the first time in 1921. This is the only vaccine that can protect against tuberculosis and is usually given to newborns as part of their standard vaccine schedule. The BCG vaccine is also used to help protect against other bacteria-related illnesses like leprosy and Buruli ulcer. Interestingly, it is also used in the treatment of a type of bladder cancer that’s only on the surface of the bladder.
The BCG vaccine is generally safe and doesn’t usually cause severe side effects. It works by protecting against future bacterial infections, like tuberculosis. Even if you’ve previously had a different bacterial infection or even tuberculosis itself, it can still help protect against future cases of tuberculosis. If you’ve already had tuberculosis in the past, the vaccine can provide up to 80% protection against getting it again. However, there is a higher chance of getting tuberculosis again if you’ve had active tuberculosis disease in the past, whether you have HIV or not. Additionally, the BCG vaccine has been linked to a decrease in deaths among children, which can’t be attributed solely to its prevention of tuberculosis. This lowering of deaths might be related to changes in a part of the immune system, known as the nucleotide-binding oligomerization domain (NOD2) receptor.
The BCG vaccine is typically given either directly under the skin or in-between layers of the skin. Researchers are currently investigating if it might be more effective to give the vaccine through the respiratory system. This is because the bacteria that causes tuberculosis typically infects humans through the respiratory system.
Why do People Need Bacillus Calmette Guerin
The BCG vaccine, which fights against tuberculosis (TB) – a severe lung infection, is recommended for various groups of people:
In children, especially newborns and infants, the BCG vaccination can be very beneficial. This includes babies and children up to five years old who are at a high risk of being exposed to active lung TB. It is also suitable for healthy newborns and school-age children (aged 7 to 14) who have not been vaccinated before.
In developed countries, this vaccine should be considered for infants and children up to five years old, if they’re in scenarios where they may be exposed to TB for a long time from a patient with untreated TB or resistant TB, and if it is not possible to keep them away from such exposure.
People who are traveling, health care workers, or community members who might be exposed to multidrug-resistant (meaning they can’t be treated by most antibiotics) tuberculosis should also consider getting the vaccine. This is highly recommended for those who haven’t been vaccinated and have not yet been exposed to tuberculosis.
In the United States, health care workers aren’t usually given the BCG vaccine as routine since the rate of TB infection is low. Additionally, the BCG vaccine can interfere with the skin test that’s used to check if a person has TB. However, health care workers from low-risk countries who are taking care of patients in countries where TB is more common might need the vaccine.
Whether you should get the BCG vaccination depends on how common TB is in your country. In regions where a lot of people have TB, newborn children should get the vaccine as a routine. But in countries with a low to moderate rate of TB, the vaccine should be given only to children who are at a higher risk of exposure.
The World Health Organization recommends that in countries with a lot of TB infection, all newborns should be vaccinated. People who are in close contact with infected patients and health care workers exposed to resistant TB infections who have negative skin tests should also get the BCG vaccine. Whereas, in countries with less TB infection, routine BCG vaccination is not suggested. For example, in the United States where TB infection is low, routine BCG vaccination is not recommended. In the United Kingdom, from 1953 to 2005, all newborns from high-risk groups and all 13-year-olds were vaccinated, but this was discontinued in 2005 due to a fall in TB infection.
In addition to preventing TB, the BCG vaccine can also be used to treat some non-invasive forms of bladder cancer. The vaccine, containing a strain of bacteria called M. bovis bacillus Calmette-Guérin, is administered directly into the bladder where it can help delay and prevent the growth of cancer cells.
When a Person Should Avoid Bacillus Calmette Guerin
BCG is a type of vaccine that’s alive and it’s not suitable for everyone. This includes those with weakened immune systems due to certain medical conditions or treatments. Here are some examples:
- People born with conditions that weaken their immune system or people with HIV, which can damage the immune system.
- People with cancer or those taking medications that suppress the immune system, such as drugs that block tumor necrosis factor-alpha, a substance that can lead to inflammation and corticosteroids, a type of anti-inflammatory medicine.
- Adults with HIV who live in places where TB (tuberculosis), a bacterial lung disease, is not common.
For these groups of people, the BCG vaccine could potentially cause more harm than good.
Possible Complications of Bacillus Calmette Guerin
Injection site reaction is the most frequent issue that can occur after vaccination. This reaction can involve different symptoms. For instance, granulomatous lesions, which are small areas of inflammation in tissue, and lymphadenopathy of regional lymph nodes, which is swelling of the glands that help your body fight infections. There could also be nodules, which are small lumps, or ulcers at the vaccination spot. Sometimes, these spots might even drain fluid or create an abnormal connection to the skin surface, known as a fistula. If a wound culture gets taken – a lab test that checks for bacteria or other organisms – it often shows the presence of Mycobacterium bovis, a type of bacteria.
There are also some potential side effects of BCG, a common vaccine against tuberculosis. For instance, suppurative lymphadenitis, a severe infection that causes pus-filled swollen glands, can occur. Children with weaker immune systems have a higher risk of having this severe swelling and infection, so it is recommended to avoid such vaccinations in these cases.
Other complications of BCG vaccination include osteitis and osteomyelitis, both of which are types of bone inflammation. In people with weakened immune systems, such as in HIV infection, the infection can spread throughout the body. This whole-body infection is known as a disseminated infection. It is, therefore, crucial for individuals with these underlying conditions to communicate with their doctors before receiving any vaccinations.
What Else Should I Know About Bacillus Calmette Guerin?
The BCG vaccine, which helps protect against tuberculosis (TB), can result in a strong reaction on a skin test called a tuberculin skin test (TST). This is particularly the case if the vaccine was given after a person’s infant years. The skin reaction can last up to 55 years after getting the vaccine.
However, if you received the BCG vaccine as a newborn and it’s been more than ten years since your vaccination, that shouldn’t affect how your skin test results are interpreted. This is especially true if you come from an area where TB is common. A different test, known as an interferon-gamma release assay (IGRA), should be used in people with a history of BCG vaccination, because BCG administration doesn’t affect this test.
Interestingly, individuals who had previous BCG vaccinations might show increased TST reactivity if they’re exposed to the test multiple times. This could result in a positive skin test even if you had a negative test previously. Also, more than half of the patients treated with BCG for bladder cancer have a positive skin test. But exposure to BCG in this way shouldn’t give a positive IGRA result.
The need for a booster vaccine comes from the fact that immunity tends to decrease 15-20 years after receiving the BCG vaccine as an infant. However, research has shown that a booster dose of the BCG vaccine wasn’t very effective in preventing TB disease, but it might offer protection against infections caused by other types of bacteria.
Studies have shown that getting the BCG vaccine reduces the chances of getting a disease called leprosy by 50 to 80 percent and this effect increases with booster doses of BCG. Earlier studies showed that the vaccine also halved the risk of getting a disease known as Buruli ulcer, but recent research hasn’t supported this finding.
The BCG vaccine also helps guard against a condition in children called lymphadenitis, which is caused by the M. avium complex bacterium. Since people stopped giving their children the BCG vaccine, more kids have been getting lymphadenitis due to certain bacteria that don’t cause TB.
Most people who’ve gotten the BCG vaccine can expect a skin reaction of 3 to 19 mm in size on the TST test two to three months after vaccination. But a study found that only 8 percent had positive skin test results 10 to 25 years after receiving the BCG vaccine.