NEW YORK (Dispatches) -- Worldwide, more people die from tuberculosis than any other infectious disease, even though the vast majorities were vaccinated. The vaccine just isn't that reliable. But a new study finds that simply changing the way the vaccine is administered could dramatically boost its protective power.
Researchers at the University Of Pittsburgh School Of Medicine and the National Institute of Allergy and Infectious Diseases (NIAID) discovered that intravenous TB vaccination is highly protective against the infection in monkeys, compared to the standard injection directly into the skin, which offers minimal protection.
"The effects are amazing," said senior author JoAnne Flynn, Ph.D., professor of microbiology and molecular genetics at the Pitt Center for Vaccine Research. "When we compared the lungs of animals given the vaccine intravenously versus the standard route, we saw a 100,000-fold reduction in bacterial burden. Nine out of 10 animals showed no inflammation in their lungs."
Flynn's team tested several routes and doses of the only commercially available human TB vaccine, Bacille Calmette-Guérin (BCG), which is made of a live, weakened form of TB bacteria found in cattle.
The BCG vaccine has been around for 100 years and is among the most widely used vaccines in the world, but its efficacy varies widely.
To test whether the method of administration matters for TB, Flynn and colleagues separated their colony of monkeys into six groups: unvaccinated, standard human injection, stronger dose but same injection route, mist, injection plus mist, and finally, the stronger dose of BCG delivered as a single shot directly into the vein.
Six months later, the researchers exposed the animals to TB and monitored them for signs of infection.