LAURAN NEERGAARD - AP Medical Writer

WASHINGTON (AP) -- Tuberculosis kills more than a million people a year, mostly in poor countries.

The only vaccine protects babies but is far less effective at preventing teens and adults from getting the deadly lung infection.

In tests with monkeys, researchers found the vaccine worked dramatically better when injected straight into the bloodstream instead of today's skin-deep shot.

More safety studies are needed before the approach is tested in people.

Wednesday's findings are in the journal Nature.