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Improved TB Vaccine in Works as Global Infection Rates Fall

  • Gabe Joselow

Children participate in the launch of a global plan to stop tuberculosis, in Alexandra Township, north of Johannesburg, South Africa, October 2010. (file photo)

Children participate in the launch of a global plan to stop tuberculosis, in Alexandra Township, north of Johannesburg, South Africa, October 2010. (file photo)

With tuberculosis infection rates falling around the world, health officials are pressing to build on those gains. One project in development aims to create a better vaccine to stop the disease for good.

The latest World Health Organization report on tuberculosis shows the number of people contracting the disease fell to 8.8 million in 2010, down from nine million five years earlier. Most of those gains have been made in some of the worst-affected areas of East Africa - notably Kenya and Tanzania.

Better treatment is largely responsible for decreased infection rates. Medical officials are not just looking for ways to treat TB, however, but to prevent it altogether.

Intensified vaccine initiative

There are several projects underway to create a more effective vaccine. The WHO says there are 10 top contenders being tested right now. One of them has been developed by the U.S.-based company Aeras.

“Our aim is to enroll 4,000 infants by the end of next year and hopefully we'll have a vaccine that works better than the current vaccine," said Vicky Cardenas, a clinical product director for Aeras, which currently is testing its new drug in five countries in Sub-Saharan Africa. "The current vaccine is called BCG and it's delivered at birth to infants, but it doesn't protect very well against pulmonary tuberculosis and it doesn't protect adults against tuberculosis.”

The current vaccine, BCG has been in use since 1921. Many of the treatments are at least 50 years old, and TB infections are becoming resistant to traditional medications. The new Aeras vaccine, known as Aeras-402, is in an advanced stage of its trial, and the company hopes to have a drug on the market by 2020.

Clinical trials in Kenya

Aeras is conducting clinical tests of the drug in the town of Kisumu in western Kenya at a clinic run by the Centers for Disease Control and the Kenya Medical Research Institute.

Cardenas said one of the reasons they chose Kenya for the trial is because of the country's influence in the region.

“What I was finding when I was working with Malaria vaccines is that most countries say, 'I'm not going to buy it unless you've tested it in my population.' So we have to overcome that barrier, because we obviously cannot test it in 192 countries," she said. "So what we like to do is to find countries that are like the opinion leaders for the region, and so Kenya, that's what we feel about Kenya, Kenya can lead the other countries."

Kenya also is an important testing ground because of the high risk that TB poses in to HIV-infected patients. The WHO says 41 percent of people infected with tuberculosis in Kenya also have HIV. The combination of the two diseases often is fatal.

Cross-treatment, funding

Grace Kiringa, a Kenyan doctor working on the Aeras vaccine project, said, “Of all the TB cases that we've found, about 22 percent of them were HIV infected. And yet, the HIV-infected babies are only like 60 out of a group of about 3,000 babies, yet they contribute 22 percent of the TB cases. So they're definitely at risk of contracting TB and actually, the sad thing is that most of them die before we can get the intervention to them."

According to WHO data, of the 22 so-called high-burden countries, where TB is most prevalent, nine are in Sub-Saharan Africa. South Africa is the worst-affected with 213,000 cases, followed by Kenya, with 97,000. Uganda, Tanzania and Ethiopia also are among the high-burden countries.

WHO says that while TB infection rates have dropped, the organization says more funding is still needed to extend treatment to more patients, particularly those with a drug-resistant strain of the disease.