Injecting tuberculosis vaccine into veins offers more protection in animal study, researchers say

Federal health researchers say they have discovered how to make a century-old vaccine better protect against tuberculosis, a leading cause of death worldwide.

In a study with monkeys, the researchers found that injecting the vaccine directly into the bloodstream proved far more effective than injecting it under the skin.

The researchers said administering the tuberculosis (TB) vaccine led to “unprecedented protection” against disease bacteria, noting the study’s results represent “a major step forward in the field of TB vaccine research.”

An estimated 10 million new TB cases were reported globally in 2018, according to the World Health Organization. Of those, about 1.5 million individuals died from the disease.

The only vaccine, known as the BCG, is given to infants via a needle that touches just under the skin to protect from a form of the disease. But the vaccine is far less effective at protecting teens and adults from tuberculosis that develops in the lungs.

Researchers from the National Institutes of Health, the University of Pittsburgh and other institutions studied a variety of ways to administer the vaccine, including a mist inhaled through a mask, to rhesus macaques — monkeys that have a similar reaction to TB as humans.

Six months after vaccinations, the researchers “challenged” the monkeys with the virulent TB bacteria and observed their reactions.

The study, published Wednesday in Nature, found that nine out of 10 monkeys who had BCG vaccines administered into their bloodstream were highly protected when exposed to TB bacteria. Six monkeys showed no signs of infection, while three monkeys had very low levels of the bacteria in their lungs.

Monkeys given the standard skin shot were only slightly more protected than unvaccinated animals. Researchers found that the mist didn’t provide much protection.

“In this monkey model, giving the vaccine intravenously did provide more protection against the development of TB in the lung than giving it by any other way,” said Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases. “Now that said, this is a study in monkeys and whether it can translate down the road into an effective and safe way to deliver the vaccine to literally millions of infants and young children, and perhaps also adolescents and adults, remains to be seen.”

Dr. Schaffner noted that administering TB vaccines intravenously will be much more challenging than the skin-deep shot, adding that other researchers are looking at other methods.

He said having an effective and safe TB vaccine is key, noting that tuberculosis continues to be one of the most widespread deadly infections in the world.

“So anything that has the prospect of improving a vaccine against this disease, tuberculosis, is something that is welcomed and looked at with great interest as the research program evolves,” he said.

To control tuberculosis infection and prevent disease, a TB vaccine must induce “strong, sustained responses” from the immune system’s T cells, particularly those in the lungs, according to the NIH. But the standard, skin-deep vaccine might not generate enough of these T cells in the lungs.

However, NIH researchers and their collaborators speculate that injecting the vaccine into the veins could help resolve this.

The U.S. reported 9,025 tuberculosis cases in 2018. Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis that usually attacks the lungs, but can attack any part of the body including the kidney, spine and brain.

Tuberculosis is an airborne disease and can spread when a person with TB disease of the lungs or throat coughs, speaks or sings.

⦁ This article is based in part on wire service reports.