Experimental TB vaccine a ‘game changer’ that offers new hope
Finding new ways to combat TB is particularly important for SA, where the HIV epidemic has fuelled the spread of the infectious disease
An experimental tuberculosis (TB) vaccine developed by GlaxoSmithKline (GSK) protects half the people who received it, scientists announced at the 50th union world conference on lung health earlier this week, offering fresh hope in the fight against the deadly disease.
Finding new ways to combat TB is particularly important for SA, where the HIV epidemic has fuelled the spread of the infectious disease. In 2018, SA had 301,000 new TB cases, and the disease killed an estimated 63,000 people, according to the World Health Organisation. Millions more South Africans have dormant, or latent, TB.
The trial is a game changer because it is the first time a TB vaccine candidate has been shown to offer protection to people who are already infected with the Mycobacterium tuberculosis bacillus.Mark Hatherill
The Bacille Calmette Guérin (BCG) vaccine, routinely given to babies around the world, was developed more than 90 years ago, and provides limited protection that wanes by adolescence. GSK’s candidate vaccine M72/AS01E was tested in 3,300 HIV negative adults in Kenya, SA and Zambia who had latent TB, and the results of the phase 2b trial were published in the New England Journal of Medicine this week.
Participants were either given two doses of the vaccine or a placebo, and followed for three years to see if they developed pulmonary TB. Only 13 people who received the shots got TB, compared to 26 who did not.
“The trial is a game changer because it is the first time a TB vaccine candidate has been shown to offer protection to people who are already infected with the Mycobacterium tuberculosis bacillus. Those people, about two thirds of SA adults, are at risk of progression to TB disease,” said the study’s principal investigator Mark Hatherill, director of the SA Tuberculosis Vaccine Initiative.
GSK’s experimental vaccine contains TB proteins that trigger an immune response, but the mechanism is not yet fully understood, said Hatherill.
Further research was needed to determine whether the vaccine protected people who had not yet been infected with TB and those living with HIV, and to determine whether the protection was durable. Ideally a vaccine should confer protection for at least 10 years, he said.
“These questions must be asked and answered in a bigger confirmatory trial or trials, which will need a funding commitment from government and non-governmental stakeholders worldwide. These answers will be critical in getting the vaccine to a broad market,” he said.
In a separate development, French pharmaceutical manufacturer Sanofi announced on Thursday that it had slashed the price of its TB antibiotic rifapentine by two thirds, to a net ex-factory price of $15 for eligible countries in low and middle-income countries, including SA.
The pricing agreement means SA can introduce a new regimen for preventing TB, called 3HP, which includes rifapentine and isoniazid pills, and has until now been too costly, said the health department’s deputy director-general for communicable and non-communicable diseases, Yogan Pillay.
The government hopes to begin providing a three-month course of 3HP as an alternative to the standard 12-month course of isoniazid in March 2020, Pillay said. The switch is expected to be cost-neutral, he said.
“This has huge implications, because SA is going to serve as the model for the rest of the world,” said Aurum Institute CEO Gavin Churchyard. The next step would be for generic drug manufacturers to launch fixed-dose combination pills that contain rifapentine and isoniazid.
“We are hoping that will bring the price down even further,” Churchyard said.