Hope for patients as GSK licenses new TB vaccine

Patients await a check-up during the launch of Kenya Tuberculosis Prevalence Survey at Mshomoroni area of Mombasa, in Kenya. PHOTO | FILE | NATION MEDIA GROUP 

In Summary

• There is no effective way to prevent the spread of TB, which is a contagious bacterial disease, and tools for diagnosing and treating the disease are also inadequate.
• The World Health Organisation recommends vaccinating HIV-uninfected infants with BCG as it provides protection against severe extra pulmonary (non-lung) forms of paediatric TB.
• However, BCG is unreliable in protecting against pulmonary TB, which accounts for most of the disease burden worldwide.

By ANGELA OKETCH
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Pharmaceutical firm GlaxoSmithKline has licensed a new tuberculosis vaccine to the Bill & Melinda Gates Medical Research Institute (MRI), paving way for the continued development of the vaccine M72/AS01E and its potential use in low-income countries with high TB burdens.

Currently, there is no effective way to prevent the spread of TB, which is a contagious bacterial disease, and tools for diagnosing and treating the disease are also inadequate.

The only existing vaccine against tuberculosis, Bacille Calmette-Guérin (BCG), created in 1921, has variable protective efficacy. The World Health Organisation recommends vaccinating HIV-uninfected infants with BCG as it provides protection against severe extra pulmonary (non-lung) forms of paediatric TB.

However, BCG is unreliable in protecting against pulmonary TB, which accounts for most of the disease burden worldwide.

The M72/AS01 vaccine candidate contains the M72 recombinant fusion protein, derived from two Mycobacterium tuberculosis antigens (Mtb32A and Mtb39A), combined with the Adjuvant System AS01.

The MRI will take the lead on future vaccine candidate development and GSK will provide the AS01 adjuvant for this programme.

The vaccine candidate demonstrated in a phase IIb trial the potential to reduce active pulmonary TB by half in adults with latent TB infection. (Latent TB means that the general public is more exposed to the infectious disease as it could become manifest at any time.)

WHO recommends that inactive TB be treated as soon as it is discovered to stop bacterial progression to the active stage.

Tuberculosis is a contagious disease which is caused by bacteria that spread from person to person through tiny droplets released into the air.

WHO guidelines require that medics test for TB after a patient is presented with symptoms like coughing, weight loss, night sweating or is HIV positive. The population also takes precautions based on these symptoms.

In the region, Kenya, Uganda and Tanzania are among the high burden Tuberculosis and HIV countries, according to WHO data.

However, Kenya is also mentioned among the 30 high Multidrug Resistance TB burden countries.

A country’s burden of TB can be described by saying how many cases of TB they have in a year. It can also be described by saying how many people in the country die of TB each year. A third way of describing it is to say how many cases of TB there are at any given point in time. The burden of TB is also sometimes related to the population size.

Several vaccine candidates are currently at different stages of preclinical or clinical development.

The most advanced candidate, a poxvirus (“Modified Vaccinia Ankara”, MVA)-vectored vaccine expressing the immune-dominant Mycobacterium tuberculosis antigen 85A, developed by Oxford-Emergent consortium, has recently been evaluated in an infant phase IIb “Proof-of-concept” trial in South Africa.

Though the number of deaths is falling, the currently estimated global rate of TB decline remains about two per cent. This rate is insufficient to achieve the 2030 United Nations Sustainable Development Goals target of an 80 per cent reduction in TB compared with 2015.

TB in HIV-negative adults with latent TB infections by half.

Dr Thomas Breuer, Chief Medical Officer of GSK Vaccines said the new vaccine will accelerate progress toward ending the TB epidemic and one of the UN’s Sustainable Development Goals.

There is no approved vaccine capable of preventing pulmonary TB disease in adolescents and adults, who accounted for 89 per cent of people who fell ill with TB in 2018.

The live attenuated vaccine, BCG, has been in use for nearly a century, and while it is effective in preventing severe TB disease in infants and young children, it provides limited protection against pulmonary TB in adolescents and adults.