Saturday, 3 Dec 2022

BCG vaccine prevents tuberculosis in young children, but not adults

Amid longstanding debate on the effectiveness of the tuberculosis vaccine, a new study suggests that the vaccine is protective against TB in children under 5, but adolescents and adults in high-burden countries may need additional protection to maintain immunity beyond childhood.

The tuberculosis (TB) vaccine, bacille Calmette-Guérin (BCG), is one of the most widely administered vaccines across the globe. Nearly 100 years old, it is the only vaccine ever administered to treat TB, which afflicts more than 10 million people each year.

Despite the age and widespread use of the BCG vaccine, there is still considerable debate on its effectiveness in preventing TB, and how long immunity may last after it is administered in infancy. And as experts study and propose new TB vaccines to supplement the BCG vaccine, an important consideration is the age at which these new vaccines should be administered to high-risk populations.

Now, a new study led by a Boston University School of Public Health (BUSPH) researcher provides new insight and clarity on these issues.

Published in The Lancet Global Health, the study found that BCG vaccination at birth does provide significant protection against TB disease — but only among children under 5 years old. The vaccine provided no protection among adolescents or adults in this study.

These results suggest that protectiveness from the BCG vaccine may begin to wane as children get older and, thus, children over 10 years old and adults should receive a booster BCG vaccine — and eventually a new, supplemental vaccine, as the researchers note that the BCG booster may also have limited efficacy — for immunity against TB beyond childhood. Unfortunately, a BCG booster has limited efficacy, so new vaccines are needed.

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