Scientists think they can make a century-old tuberculosis vaccine far more protective simply by changing how they give itanimals’ lungs and watched for infection. Monkeys given today’s standard skin shot, even with a higher dose, were only slightly more protected than unvaccinated animals, and the mist wasn't too effective, either.
But in 9 of 10 monkeys, a higher-than-usual vaccine dose injected into a vein worked much better, the researchers reported in the journal Nature. The team found no trace of infection in six of the animals and counted very low levels of TB bacteria in the lungs of three.
Why? The hypothesis is that key immune cells called T cells have to swarm the lungs to kill off TB bacteria and can do so more quickly when the vaccine is carried rapidly around the body via the bloodstream. Sure enough, tests showed more active T cells lingering in the lungs of monkeys vaccinated the new way.
The findings are striking, showing that how a vaccine is given “clearly affects immunity,” University of Massachusetts TB specialists Samuel Behar and Chris Sassetti, who weren’t involved in the study, wrote in an accompanying editorial. Still, giving a vaccine intravenously isn’t nearly as easy as other kinds of shots, they cautioned.
Seder said additional safety research is underway in animals, with hopes of beginning a first-step study in people in about 18 months.
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