A vaccine that can "revolutionize" tuberculosis treatment has been launched by researchers.
It is hoped that the vaccine will provide long-term protection against the disease, which kills 1.5 million people worldwide each year.
This highly contagious disease is caused by bacteria, and the current vaccine, the BCG puncture, is not very effective.
However, while initial trials have proven successful, the vaccine is still a few years away from licensing.
The research team, who came from all over the world, revealed a vaccine, consisting of proteins from bacteria that triggers an immune response, during a global summit on lung health in the southern Indian city of Hyderabad on Tuesday.
- Are there adequate global efforts to fight TB?
- Living with drug-resistant TB in India
This has cleared the critical phase of clinical trials and has been tested on more than 3,500 adults in TB endemic areas in South Africa, Kenya and Zambia, the researchers said.
Why is the vaccine "revolutionary"?
David Lewinsohn, a TB expert, told the BBC the potential of the vaccine was "a real game changer".
"What is truly remarkable is that it is effective in adults who have been infected with Mycobacterium tuberculosis which is a causative agent of TB," he said.
"Because most people infected with Mycobacterium tuberculosis do not get TB, we believe that the infection provides some level of protection. As a result it is very interesting that a vaccine has been shown to increase this natural immunity. "
Dr Lewinsohn said the new vaccine had cleared the key "development of the middle phase, and was designed to test safety and to provide early indicators of efficacy".
"It is very likely that vaccines need to be tested in additional populations, and perhaps larger trials before being licensed. Assuming the data persisted in the remaining trials, which seemed possible, this vaccine had the potential to revolutionize TB treatment. "
How long will the vaccine be on the market?
Dr. Lewinsohn estimates that, if all goes well, the vaccine will reach the people who need it most around 2028.
The researchers said that proving that vaccine work often requires studies that are far greater than those needed for viral diseases such as measles. The drug company GlaxoSmithKline (GSK) has been working on TB vaccines for almost 20 years.
To develop, the vaccine must show efficacy in animals, usually mice, but also guinea pigs and non-human primates.
One reason developing TB vaccines is a challenge, the researchers say, is that "animal models often do not reflect what we want to see in effective vaccines".
For example, in mice, TB tends to be a "lazy disease" and researchers might define success as a 10-fold reduction in the number of bacteria in the lungs.
This is encouraging, but children with one tenth of the bacteria still have TB.
How serious is the current situation?
In 2018 an estimated 10 million people will become ill with TB, according to the World Health Organization (WHO).
Nearly a quarter of the world's population suffers from latent TB infection. This means they carry bacteria in an inactive, non-sick and infectious form to others. People with latent TB have a 5 to 10% risk in their lives to develop active TB.
Meanwhile, multi-drug-resistant TB (MDR-TB) – a type of TB that is unresponsive or resistant to at least two of the first-line anti-TB drugs – continues to be a major public health threat. Drug-resistant TB is more difficult and more expensive to diagnose and treat.
WHO aims to reduce the number of new TB cases by 90% and the number of TB deaths by 95% between 2015 and 2035.
Which country is worst affected?
Eight countries make up two-thirds of global TB cases: India (27%), China (9%), Indonesia (8%), Philippines (6%), Pakistan (6%), Nigeria (4%), Bangladesh (Bangladesh) . 4%) and South Africa (3%).
With a little more than one of the four estimated global cases, India has the highest TB case burden in the world.
The country records nearly three million new TB cases each year, more than 100,000 of which are multi-drug resistant, according to WHO.
The disease also kills 400,000 Indians every year, and costs the government about $ 24 billion ($ 18.68 billion) per year.
"We cannot eliminate TB globally unless we end it in India," said Jamhoih Tonsing, director of the International Union Against Tuberculosis and the Lung Disease office in Delhi.
The union is the organizer of the 50th World Union Conference on Lung Health held in Hyderabad this week.
"The number of people with TB in India is falling and that is good news. But to be honest – TB is still not falling fast enough in India, progress is still too slow to meet targets. We need to improve treatment and prevention measures," he said.
- TB is a bacterial infection that spreads by inhaling small drops from coughing or sneezing in an infected person.
- It mainly affects the lungs, but can affect any part of the body, including the stomach glands, bones and nervous system.
- The most common TB symptoms are persistent coughing for more than three weeks, unexplained weight loss, fever and night sweats.
- TB is difficult to catch and you have to spend hours in close contact with people with infectious TB to risk being infected
- TB can be fatal if not treated – but can be cured if treated with appropriate antibiotics for six months
- The BCG vaccine offers protection against TB, and is recommended for infants, children and adults under the age of 35 who are at risk of contracting TB.
- Risk groups include: children living in areas with high TB rates and people with close family members from countries with high TB rates