The success of the GSK vaccine is an important step in the fight against tuberculosis, but can still be improved

LONDON (Reuters) – An experimental GlaxoSmithKline vaccine could prevent the development of TB in half of the cases, potentially making it the first vaccine against the global killer in a century, researchers said Tuesday.

Given the failure of other candidates in recent years, it marks a milestone in the fight against tuberculosis, even though the 54% effectiveness rate achieved in adults in an intermediate clinical trial is low compared to vaccines against other diseases.

The current vaccine called Bacillus Calmette-Guerin (BCG) was developed in 1921 and is routinely given to babies in countries with high TB ​​rates to prevent serious diseases.

However, BCG protection dissipates in just a few years and does not protect against the most common form of TB that invades the lungs of adults and adolescents and can be transmitted by coughing and sneezing.

Experts believe that a more effective vaccine is essential for fighting tuberculosis and fighting the growing scourge of drug-resistant infections. Tuberculosis is a major goal of global health, the United Nations is organizing its first high-level meeting on the disease in New York on Wednesday.

GSK's vaccine is designed to prevent latent TB becoming active and causing disease. An estimated 1.7 billion people – a quarter of the world's population – have latent TB infection, leaving them vulnerable to a disease that killed 1.6 million people last year.

The results of a Phase IIb trial of the vaccine – known as M72 / AS01 and developed by GSK in collaboration with Aeras, a nonprofit group supported by the Bill & Melinda Gates Foundation – have been published in line by the New England Journal of Medicine.

After an average follow-up of 2.3 years, 10 of 1786 adults vaccinated twice developed active pulmonary tuberculosis, compared with 22 of 1787 who received two injections of placebo. The study was conducted in Kenya, Zambia and South Africa.

The vaccine produced more side effects than placebo, with two-thirds of participants reporting at least one adverse event, usually injection site reactions or flu-like symptoms.

Most of the volunteers had received the BCG vaccine and all were HIV-negative. People living with HIV are more vulnerable to TB because their immune systems are weakened.

Jacqui Shea, Regional Director General, said the results were "innovative" and that more effective TB vaccines were feasible.

GSK is confident that it can do better in the future, with larger trials aimed at refining the vaccine dosing schedule and potentially targeting specific groups of patients most likely to benefit.

"This is the first time that we have really tested the biological potential of our vaccine and we think there are many more improvements to be made now," the company's vaccine researcher told Reuters. , Emmanuel Hanon.

Tuberculosis is a particularly delicate disease to vaccinate because the bacteria that cause it can hide from the immune system and scientists do not have protective markers in the blood to predict how a vaccine works.

As a result, TB vaccines need to be tested in large clinical trials, a major and expensive gamble.

Mike Turner, Infection and Immunobiology Manager at the Wellcome Trust, said the encouraging results were a "defining moment" and that M72 / AS01 should now be tested on a much larger number of people. .