Why do I get tuberculosis even though I have been vaccinated?

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Hello doctor. My son was born in 1999. In November 2019, he went to the hospital for regular health check-ups and had a chest X-ray, the results were normal. Last week, when she went to the central hospital, she was diagnosed with tuberculosis. She was vaccinated against tuberculosis when she was born, why is she still sick? Ask your doctor for advice. I would like to thank you.
Nguyen Thu (1974)
Reply
Hello!
Vaccination against TB is an effective method, but not absolute. In fact, the TB vaccine belongs to a strain of attenuated bovine tuberculosis bacteria, so it has the ability to cause cross-immunity with TB bacteria existing in the human body due to the same antigens.
Therefore, TB vaccine may not help us against the invasion of TB bacteria that cause disease, but it can minimize the risk of converting from infectious form to tuberculosis (about 70%). ) and almost absolutely prevent the occurrence of dangerous tuberculosis complications such as tuberculosis of bones, tuberculosis of joints, tuberculosis of lungs, tuberculosis of meninges.
Whether TB vaccination is effective or not depends on management preventing TB transmission in the community. People who have been vaccinated against TB can get the disease through direct, frequent, and long-term contact with an infected person. However, people who have been vaccinated in case of infection are usually milder and treated more quickly than those who have not been vaccinated.
Thank you for sending your question to Vinmec Health System. Best regards!