After nearly 100 years, researchers could be on the verge of finding a vaccine that would eradicate tuberculosis infections, a scourge that kills 1.4 million people a year.
If it turns out to be at all positive, it will be a clear watershed for the field
Global health experts are eagerly awaiting clinical trial results, expected early next week, of the first new vaccine in 90 years designed to prevent tuberculosis infections. While it might not prove effective, it will bring scientists much closer to creating a new generation of TB vaccines.
Known as MVA85A, the vaccine is the farthest along of more than a dozen candidates being developed globally to stop the transmission of mycobacterium tuberculosis, which is quickly outsmarting the best antibiotic weapons used against it.
“In my own personal view, I will consider this (trial) to be a landmark or a watershed,” said Peggy Johnston, senior programme officer at the Bill & Melinda Gates Foundation in Seattle.
“If it is negative, it would be the first trial we can demonstrate that yes, we can conduct a clinical trial and get a solid answer. If it turns out to be at all positive, it will be a clear watershed for the field.”
Although companies are making strides in developing new drugs to fight TB, such as Johnson & Johnson’s recently approved drug, bedaquiline, experts believe a vaccine ultimately will be the best tool to eradicate the ancient disease, which infects nine million people a year.
“Drug development at the moment is lagging the rate at which drug resistance is emerging. We can’t constantly be chasing after the next drug that becomes ineffective,” said Christine Sizemore of the National Institute of Allergy and Infectious Diseases, a part of the National Institutes of Health.
Ann Ginsberg of Rockville, Maryland-based Aeras, a non-profit biotech developing MVA85A said it is “the single tool that could have the greatest potential impact on theTB epidemic”.
Ginsberg said better drugs will be useful to treat people who are already sick, but by the time a person with TB is diagnosed, they have already infected 10 to 15 people.
“A vaccine can stop transmission,” she added.
A lot is riding on the trial’s results, which will give the first solid clues about whether scientists are on the right track to create a new generation of TB vaccines.
MVA85A is being developed by researchers at Britain’s Oxford University with support from Aeras, the Wellcome Trust, the European Commission and the Oxford-Emergent Tuberculosis Consortium, a joint venture between Oxford and Emergent Biosolutions Inc. created to make the vaccine.
It is one of 16 vaccines being studied in human clinical trials and the study results will inform the design of more than 50 vaccines being tested in preclinical trials in animals.
Most of the development has occurred in the last decade with the emergence of drug-resistant TB, which could affect as many as two million people by 2015, according to the World Health Organisation.
Treating typical TB is a long process, with patients needing to take a cocktail of antibiotics for six months. Many fail to complete treatment and that has given rise to drug resistance.
Multi-drug resistant TB withstands two standard drugs, but a more severe form known as extensively drug-resistant TB, which thwarts the most highly effective drugs, was reported in at least 77 countries in 2011, the WHO said.
And doctors in India have begun reporting cases of totally resistant TB, in which no effective drugs are available.
“This previously neglected disease has now come to the forefront,” said Johnston of the Bill & Melinda Gates Foundation, which provides the bulk of the funding for Aeras.
“That has stimulated new investment not only in new drugs to treat those resistant strains, but also in vaccines to give us a longer-term solution.”
Part of what makes TB so difficult to treat is that it has evolved along with humans and hides in human cells.
“Mycobacterium tuberculosis is a wily foe,” Ginsberg said. “A third of the world is already infected with this bug and some 10 per cent will get sick and pass it on to others.”
It is that large reservoir of future TB cases that vaccine makers hope to protect, along with those who have never been exposed.