World Health Matters (China): TB on the rise in older people

by Gary Finnegan: Preliminary findings presented at an international TB vaccine conference suggest older people are contributing to TB rates in China. Researchers say the development and introduction of a ‘post-infection’ vaccine could have a major impact in reducing TB disease in the world’s most populous country.

The WHO currently estimates that nearly 1 million new cases of TB are recorded in China every year. A new study led by the London School of Hygiene & Tropical Medicine suggests that the number of new cases in the elderly will continue in the coming decades.

Scientists at the Fourth Global Forum on TB Vaccines in Shanghai said a post-infection vaccine could reverse the current trend by almost a third by 2050. Globally, 2050 is the target year for eliminating TB as a public health problem.

China is acknowledged to have made a great deal of progress in controlling the disease over the last 20 years, but it is still hard hit by the TB epidemic.

“We chose to study TB trends in China given the magnitude of the disease burden present and the anticipated increase in the number and proportion of elderly people within the population,” said Rebecca Claire Harris, an epidemiologist with the London School of Hygiene & Tropical Medicine in the UK, who presented the results. “We wanted to understand how these factors would affect the attempt to eliminate TB in the country.”

This is the first time the possible impact of giving new TB vaccines to older adults has been considered in any setting, and could inform how future clinical trials and vaccine deployment plans are developed, she said.

Preliminary study results predict that the elderly (those aged 65 years and above) contribution to TB infection transmission in China may increase from 18 percent to 53 percent, and their burden of TB disease may increase from 13 percent to 71 percent of all new TB cases.

“Targeting older adults is a departure from the current thinking in the field, which mostly focuses on developing vaccines for children and adolescents. This also may be different from other parts of the world, such as sub-Saharan Africa, where there is much more disease in young adults,” said Harris.

BCG, the nearly 100-year-old existing TB vaccine, works most consistently in infants and is largely ineffective against the most common and contagious form of the disease, that is, TB in the lungs. Decades of widespread use of this vaccine has failed to control the global TB epidemic, leading researchers globally to work on development of new, more effective TB vaccines.

The two non-profit organizations at the forefront of this vaccine development work, the U.S.-based Aeras and the Netherlands-based TuBerculosis Vaccine Initiative (TBVI), helped organise the international gathering of TB and TB vaccine experts in Shanghai.

“Tuberculosis is a major public health threat, tied with HIV as the leading cause of death globally among infectious diseases, with antibiotic resistance a major treatment challenge, yet we are years behind where we should be in vaccine development due to lack of acknowledgement of the TB health threat and the resultant lack of investment in new tools,” said Tom Evans, CEO of Aeras.

“One of the reasons the global TB vaccine community is excited to meet in China is the level of commitment we’ve seen from the authorities here to innovative research, including developing the world’s only TB vaccine candidate currently in a Phase 3 trial.”