Injecting into vein may boost TB vaccine

In the constant search for a vaccine against tuberculosis — which now kills more people around the world than any other infectious disease — researchers have made an unusual discovery.

In tests on monkeys, they found that an almost century-old vaccine routinely given to infants in many countries is far more protective when injected into a vein rather than by the normal route, just under the skin. Routine childhood vaccinations are not generally injected into a vein.

Injecting the vaccine into a vein completely protected 9 of 10 monkeys who were exposed to large doses of live TB germs six months later, according to the study. The research was led by scientists from the University of Pittsburgh’s medical school and the National Institute of Allergy and Infectious Diseases and published Wednesday by the journal Nature.

The tuberculosis vaccine is made from a live, weakened form of the tuberculosis bacteria found in cattle. It has been in use since 1921, is made by many companies and costs as little as $1 a dose for use in developing countries. It is considered safe even for newborns.

However, it is not very effective. It protects infants against some devastating forms of TB but eventually wears off and does not protect adolescents or adults against lung infections, the illness that kills most TB victims.

Several experts not involved in the study said they were impressed by the results, although they warned that much more testing remains to be done.

“If this is shown to be as efficacious in humans as it is in the monkeys, the potential will be huge,” said Dr. Mario Raviglione, director of the University of Milan’s Global Health Center and a former director of the World Health Organization’s tuberculosis programs.