UK researchers have found the BCG vaccine to be more effective against the most common form of tuberculosis than previously thought.
BCG (Bacillus Calmette Guérin) is the only licensed vaccine against tuberculosis. However, it was thought to only be effective against the less common forms of the disease that occur away from the lungs.
Its efficacy against pulmonary TB, found in the lungs and by far the greatest burden of TB, has varied widely depending on location, ranging from 0% in South India to 80% in the UK.
Researchers, led by the London School of Hygiene and Tropical Medicine, conducted a systematic review of BCG trials, looking at the factors affecting its level of protection against pulmonary TB.
The research shows for the first time that the BCG vaccine is actually highly protective against pulmonary TB in all parts of the world.
The main reason for the apparent variation in protection against disease seen in previous studies was found to be due to prior infection reducing the efficacy of the vaccine, the study authors.
BCG vaccination for those with no history of prior TB infection, including young infants, showed a much higher efficacy against pulmonary TB.
Lead author Dr Punam Mangtani, clinical senior lecturer in epidemiology at the London School of Hygiene and Tropical Medicine, said: “This research corrects a longstanding misconception that BCG is ineffective against pulmonary disease, and confirms its importance in controlling the major burden from TB and main source of transmission in all settings.
“Now that we know previous infection can lower the protection provided by the vaccine, it is important that BCG is given as early as possible in a person’s life, and ideally immediately after birth,” she added.
The research was funded by the UK National Institute for Health Research Evaluation, Trials and Studies Coordinating Centre. It is published in the journal Clinical Infectious Diseases.
The BCG vaccine is not given as part of the routine NHS childhood vaccination schedule unless a baby is thought to have an increased risk of coming into contact with TB, such as those born in some areas of inner-city London.
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