New TB vaccine protects before and after infection

Danish scientists have developed a new vaccine that can fight TB before and after infection.

London: Danish scientists have developed a new vaccine that can fight tuberculosis (TB) before and after infection.

It could offer protection for many years more than is now possible, reports the BBC.

TB is a disease of the lungs, causing symptoms such as coughing, chest pains and weight loss. Untreated, it can be deadly.

However, only in a small number of cases - fewer than 5 percent - do the symptoms develop immediately after infection.

In more than 90 percent of cases, once Mycobacterium tuberculosis, the bacterium that causes the disease, has invaded the body it changes its chemical signature, and lives in a dormant - or "latent" - state.

Usually the bacterium never emerges from this latent state, but in around 10 percent of cases it reactivates - often years or even decades later - to trigger severe symptoms.

Current vaccines, such as the BCG vaccine, work only if given before exposure to the bacterium. They do not prevent infection, but do prevent acute symptoms and disease from emerging.

But once the bacterium has changed into its latent form it is effectively immune to the vaccine, and can bide its time, reactivating after the vaccine has ceased to have a preventative effect.

The latest vaccine- so far tested in animals- if successful in human trials, would be able to tackle that problem.

Developed by a team at the Statens Serum Institute in Copenhagen, it combines proteins that trigger an immune response to both the active and latent forms of Mycobacterium.

"It might be possible to give a booster jab post-exposure to older children or even young adults. which would protect them well into adulthood." researcher Peter Lawætz Andersen said.

The study appeared in the journal Nature Medicine.