New efficacious vaccine to fight TB on the horizon

By Dr T V Venketasawaran and Jyoti Singh

New Delhi: Scientists hope to have a formidable weapon against tuberculosis in the form of a new vaccine very soon.

Called VPM 1002, the vaccine is based on the BCG vaccine that is in use. Only, it promises to be more powerful and efficacious. BCG provides protection to children and not to young people or adults. The new vaccine promises to overcome this problem.

Director in-charge of National Institute for Research in Tuberculosis (NIRT) in Chennai, Dr Srikanth Prasad Tripathy, expressed confidence that the new vaccine promises to pass muster and become available for public use soon.

Image: Director in charge of National Institute for Research in Tuberculosis in Chennai, Dr Srikanth Prasad Tripathy.

If proved successful, the new vaccine would be a boon for India. The country carries the highest burden of TB. Every year 10.4 million new cases are detected worldwide and out of that 2.8 million are estimated to be in India.

Dr Tripathy notes, “In 2000, we had a TB incidence of 289 per lakh population in India. It has reduced to 217 per lakh of population this year. However, as per the goal set by World Health Organisation under the End TB Strategy set we should have reached a level of 55 per lakh population by 2015 itself. We have a long way to go”.

Besides the clinical trial for the new vaccine, several efforts are underway to tackle the growing problem of drug resistance in the country. It is estimated there are about 4.5 lakh multi-drug bacterial resistant (MDBR) TB cases worldwide and that of them, about 1.3 lakh cases were in India.

NITR has initiated studies to look at ways to reduce the high mortality rates due to drug resistance. “We may soon introduce bedaquiline based new drugs, which are effective even in MDR-TB patients. Further, another drug Delaminate seems promising even in extensively drug-resistant tuberculosis (XDR-TB) where even fluroquonine group of drugs are not effective”, Dr Tripathy said.

He noted that the Institute was also working on the issue of co-infection of TB and HIV, which is another major health problem in the country. About 40 percent of the Indian population is tuberculin positive and in the elderly the rate is higher at 70 to 80 percent. However, only 10 percent of these positive cases develop into active TB in their lifetime. Normal human immunity is able to repress the onset of the disease. Problems, however, arise when a TB positive person is also afflicted with HIV virus. HIV compromises the immune system and as a result TB bacteria residing in the body starts multiplying and causes active disease.

“We studied seroprevalence of TB among the HIV positive in Pune for the first time in 1988. We tested around 300 TB patients for HIV and found none of them were HIV positive. However in 1992, the rate went up to three percent and by 1996, 20 percent of the TB patients were HIV positive. This indicates that HIV patients needed to be tested and treated for both HIV and TB at the same time. If not they may be cured of HIV but die of TB. Further our study also showed that if we start antiretroviral therapy (ART) early we can even arrest the onset of TB in HIV positive patients” he said.

NITR’s contributions to TB research include development of a short course chemotherapy.  Earlier patients had to be treated for one and half years to two years. The regime developed by the Institute has reduced it to just six months. The cure rate is 95 per cent. The only condition is the patient has to take the medication regularly, without any gap whatsoever.

“The patients are often lulled into complacency after taking the medication for a few weeks. The symptoms disappear. Some of them stop the medicine thinking they have been cured. However the TB bacteria die very slowly and it takes about six months to kill them in toto. If the medication is stopped early, the TB bacteria still alive in the body could multiply and TB can recur and relapse. If this occur the problem is even more difficult. The TB bacteria may develop drug resistance, and then it is not easy to treat” warns Dr Tripathi.

The medical community in the country, he said, has been galvanised and several strategies are being implemented to tackle the disease. From passive case identification — waiting for the patients to come and seek medical help, the strategy is being shifted to active case finding. Both the government and private sectors are mobilised. “Identifying the patients at early stages is essential to ensure that they do not spread the disease to others. We also need to remove the stigma associated with TB. There is a need to generate public awareness”, he added.

(India Science Wire)