New Vaccines are Essential to End TB
Vaccines are one of the most successful and cost-effective public health interventions for reducing and even eliminating deadly infectious diseases. But the only licensed vaccine against TB, Bacille Calmette-Guérin (BCG), while moderately effective against TB in infants and young children, is unreliable in preventing TB in adolescents and adults, the population that bears the highest burden of disease.
A more effective vaccine is essential to ending the global TB epidemic. Mathematical modelling indicates that a new TB vaccine for prevention of disease that is 60% efficacious and delivered to just 20% of adolescents and adults globally could avert up to 60-70 million cases in its first 25 years of use. And a significantly improved infant vaccine, relative to BCG, could potentially avert approximately 6-7 million new cases of TB over that same time period.
Tackling Drug-Resistant TB: The Cornerstone of Antimicrobial Resistance
Antimicrobial resistance (AMR) is a growing public health threat, as bacteria evolve and treatments become less effective. In 2015 there were an estimated 250,000 deaths resulting from multidrug-resistant TB (MDR-TB). It is estimated that if not addressed – including through developing more effective diagnostics, drugs, and vaccines – by 2050 MDR-TB could cause 2.5 million deaths per year and cost the global economy as much as $16.7 trillion.
An effective vaccine would contribute to efforts to address drug-resistant TB in several ways:
- New vaccines are likely to be equally effective against both drug-resistant and drug-sensitive strains of TB, thus reducing incidence and transmission of DR-TB.
- By preventing disease, vaccines would reduce the need for antibiotics, which will be essential to curb the rise of antimicrobial resistance.
- Therapeutic vaccines, used in combination with drugs, could also reduce treatment duration and the risk of recurrence, which would also lead to reductions in DR-TB.
New Vaccines are Achievable
Ninety percent of otherwise healthy individuals infected with TB do not progress to TB disease. This indicates that the human body can already protect itself from TB in some cases, and scientists hope to replicate this innate resistance in a vaccine. And, the current vaccine, BCG, does offer partial protection, which is a positive indicator that it is possible to develop vaccines that offer better protection.
Significant progress has been made in the last 20 years. Twelve vaccine candidates are currently being tested in clinical trials. In addition, there are promising activities for the development of new biomarkers, and, for the first time in decades, basic information on safety and immune responses to a variety of first-generation TB vaccine candidates is available.
Success Will Require Increased Investment
Vaccine development is a lengthy and expensive process. Substantial and sustained resources are needed to support and enhance the full continuum of research and development. But, despite the urgent need for new vaccines and continued progress in the field, TB vaccine research funding in 2015 declined from $111 million to just over $80 million, the lowest level since 2010. It is estimated that at least $250 million will be needed per year to meet the objectives for TB vaccine development outlined in the Global Plan to End TB 2016-2020. This represents a fraction of the estimated $20 billion per year that the TB epidemic currently costs in diagnosis, treatment, and lost productivity, and would accelerate the development of this lifesaving intervention.
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