Instead of injecting the vaccine into the muscle or skin, researchers injected BCG directly into the bloodstream. The results were dramatically improved effectiveness.
Tuberculosis (TB) is still a deadly disease worldwide, although it is not as prevalent in the U.S. For example, in 2018, there were 10 million new cases of active TB worldwide with almost 1.5 million deaths. And what is even more surprising is that many of the people who die from TV were vaccinated as babies.
That vaccine is known as the bacilli Calmette-Guerin (BCG), and it has been given for almost 100 years. It is a live but weakened type of a similar bacteria to the Mycobacterium tuberculosis that causes TB. It is very effective in preventing certain forms of TB in children, but less so in adolescents and adults.
Investigators with the National Institutes of Health (NIH) recently conducted research on monkeys that used the same BCG vaccine, but instead of injecting the vaccine into the muscle or skin, they injected BCG directly into the bloodstream. The results were dramatically improved effectiveness.
Six months after intravenously injecting BCG, the research team infected the monkeys with TB directly into their lungs. In nine or 10 days, the IV vaccine worked better than the control group receiving the standard skin shot, even at higher doses.
The research was published in the journal Nature.
JoAnne Flynn, a professor of Microbiology and Molecular Genetics at the University of Pittsburgh, who worked on the project with Robert Seder at the NIH, wrote in The Conversation, “After two months we found that when the vaccine was delivered via IV, the numbers of specialized immune cells, called T cells, which can recognize and kill the bacteria, increased by 100-fold in the lungs.”
She added, “Then, months later, we exposed the monkeys to M. tuberculosis. Unvaccinated monkeys developed severe TB disease within a few months. BCG administered through the skin or into the lungs gave a little bit of protection, but the monkeys still had signs of TB.”
The intravenous vaccine, she noted, “provided incredible protection.”
In almost all of the animals, nine out of 10, there were no signs of M. tuberculosis bacteria. They also conducted PET-CT scans showing that the lungs of most of the monkeys had no signs of the disease. There were no traces of infection in six of the monkeys and only very low levels of the bacteria in the lungs of three others.
In general, TB vaccines only provide limited protection. Flynn notes that it’s a long way before it can be tested in this way in humans, but that these studies could be the foundation for developing new TB vaccines that could save millions of lives.
The researchers theorize that for T cells to be effective in fighting TB bacteria, they have to swarm the lungs. When in the blood stream, they are carried more quickly around the body.
Additional work is being conducted in animals to determine safety. Seder indicates he hopes to begin work in humans in approximately 18 months.
TB attacks the lungs but can damage other parts of the body. It spreads through the air when an infected person coughs, sneezes, or talks. Symptoms of TB include a bad cough lasting three weeks or longer, weight loss, loss of appetite, coughing up blood or mucus, weakness and fatigue, fever and night sweats.
