First Ever Tuberculosis Booster Vaccine Shows Promising Results

Canadian researchers have developed a new tuberculosis vaccine that could boost or perhaps replace the only existing way to immunize against the infection.

The researchers say the new vaccine is an important breakthrough because the current tuberculosis vaccine is not effective enough to curb the TB epidemic in some parts of the world.

"We are the first to have developed such a vaccine for tuberculosis," said Dr. Fiona Smaill, professor and chair of the Department of Pathology and Molecular Medicine at McMaster University.

"Tuberculosis is a serious public health threat," she said. "One-third of world's population is infected with the organism that causes tuberculosis, and it remains the top infectious killer of people, only secondary to HIV, yet the current vaccine used to prevent it is ineffective."

The control of TB has met with further challenge from the high incidence of multi-drug resistant tuberculosis, she added.

Smaill led the phase-one clinical study alongside Zhou Xing, professor of pathology and molecular medicine at the McMaster Immunology Research Centre. The findings were published Wednesday in the journal Science Translational Medicine.

The McMaster vaccine, which was developed in Xing's laboratory, is based on a genetically modified cold virus, and was designed to act as a booster to Bacille Calmette Guerin (BCG), the only TB vaccine available today.

BCG was developed in the 1920s, and is currently part of the World Health Organization's immunization program in Asia, Africa, Eastern Europe and South America, as well as Nunavut, the only Canadian jurisdiction where the BCG vaccine is routinely given because of the high rate of tuberculosis in the territory. It is typically given during the first year of life.

The new vaccine would serve as a "booster" that would reactivate immune elements that over time diminish following BCG vaccination.

The McMaster researchers have worked for more than a decade to develop their vaccine. The first human clinical trial began in 2009 with 24 healthy human volunteers, including 12 who were previously BCG-immunized.

"The primary goal was to look at the safety of a single dose vaccine injection...as well as its potency to engage the immune system," said Xing.

By 2012, the researchers established that the vaccine was safe, and had observed a robust immune response in most trial participants.

Xing said additional clinical trials are needed to measure the vaccine's true potential.

Smaill emphasized the significance of completing the phase-one clinical trial, and its potential impact.

"As a doctor who looks after patients who have tuberculosis, including those who are HIV infected, I realize how important it is going to be to control this infection with a good vaccine," she said. "We are probably one of a few groups in the world who are actually doing bench-to-human tuberculosis vaccine work, and we are excited to be part of this and thrilled that it started at McMaster."

The World Health Organization reports 8.7 million people were sickened with TB in 2011, and 1.4 million people died.

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