Over the past two decades, significant progress has been made in the fight against tuberculosis (TB). Between 1990 and 2012, TB mortality worldwide fell by 45 percent. Due to coordinated global efforts and the use of the
directly observed therapy short-course (DOTS) strategy, the recommended treatment for TB developed in the 1980s, 56 million people with TB were successfully treated between 1995 and 2012, saving 56 million lives. An estimated 1.3 million lives were saved through increases in collaborative treatment of TB and HIV between 2005 and 2011.
Despite this progress, TB remains one of the leading causes of death worldwide. In 2012, an estimated 8.6 million new cases were reported and 1.3 million people died from the disease. In recent years, TB control efforts have taken on increased urgency due to the emergence of
multidrug-resistant TB (MDR-TB), a form of the disease that is resistant to frontline drugs, and extensively drug-resistant TB (XDR-TB), which is also resistant to some second-line drugs. MDR-TB has emerged in nearly every country in the world, with an estimated 450,000 new cases in 2012. These forms of the disease are especially difficult and costly to treat and are a consequence of years of inadequate diagnosis and treatment. The TB epidemic in countries with a high rate of HIV has also accelerated. In 2012, about 320,000 people died who were co-infected with TB and HIV.
Current approaches to preventing, diagnosing, and treating TB are inadequate. The TB vaccine used today provides limited protection for newborns and children and no protection against pulmonary TB in adults, which accounts for most of the TB cases worldwide. The most commonly used diagnostic tool, the microscope, detects only half of all cases and is labor-intensive for health providers and requires special skills. Finally, while the standardized DOTS treatment regimen has had significant success, it requires the patient to take a complex combination of pills every day for six to nine months, assumes that a healthcare worker will supervise the full duration of treatment, and has significant side effects. The result is that many patients end treatment prematurely.
Currently there is only one vaccine against tuberculosis available worldwide:
Bacille Calmette-Guérin (BCG). This vaccine, used since 1921, can protect children from severe forms of tuberculosis. However, BCG has little to no efficacy in preventing pulmonary TB in (young) adults, the most common and most infectious form of tuberculosis. Moreover, there are serious safety concerns regarding the use of BCG in HIV infected newborns. More effective, safe vaccines to improve or replace BCG are urgently needed as tuberculosis keeps taking its toll. TB causes around 1.5 million deaths a year and the burden of the disease, affecting economies worldwide, is estimated at hundreds of billions of dollars annually. Vaccines – generally accepted as and proven to be both a very efficient and cost-effective way of preventing infectious diseases – can make the difference.