Rising TB rates lead to call for new vaccines

Tue, Oct 16, 2012, 01:00

OXFORD-BASED SCIENTISTS have called for more and better vaccines ahead of the publication of new figures by the World Health Organisation on the incidence of tuberculosis, which is concentrated in India, China, South Africa, Indonesia and Pakistan.

The first vaccine against TB, Bacille Calmette-Guérin, was used in 1921. It is still the only vaccine in use against a disease that kills nearly 1.5 million people each year. TB is becoming increasingly resistant to the drugs being used against it.

In the years after the second World War, the vaccine saved millions of lives in Eastern Europe after eight million children were vaccinated. The much feared epidemic of TB, seen as inevitable after wartime, was controlled by the widespread vaccination.

Though effective in preventing tuberculous meningitis in infants, BCG has a far patchier record in fending off pulmonary tuberculosis, particularly in adolescents and adults, scientists in London said yesterday.

Hopes now lie in MVA85A, a vaccine developed by Prof Helen McShane, Oxford University’s professor of vaccinology. Extraordinarily, it is the first new TB vaccine to have begun clinical trials since BCG did so 81 years ago.

Work on MVA85A has been under way for more than a decade. Next spring, Prof McShane and her team will learn the results of the first efficacy trial in South Africa – where half of the babies chosen were given the vaccine, and the other half received a placebo.

The vaccine bids to improve the effectiveness of BCG, not replace it, though the team still does not know what responses it needs to provoke in a patient’s immune system to ensure that TB can be held at bay, said Prof McShane at a briefing organised by the Wellcome Trust.

Today, however, greater mobility ensures that every national health system has to cope with TB: nearly 9,000 cases were reported in the United Kingdom in 2010, 6.6 per cent up on the year before. Three-quarters of the cases are reported by recent arrivals.

TB’s greater resistance to drugs has grown because they have often been misused; the disease has been poorly managed; and drug-resistant variations have been transmitted from person to person, said Prof Tim McHugh, director of University College London’s Centre for Clinical Microbiology.

Recently in South Africa, Dr Ann Ginsberg, who works for Aeras, a not-for-profit organisation backed by billionaire Microsoft founder Bill Gates, offered a graphic example of difficult to stop transmission when she spoke of her experience outside Durban’s main bus station.

Hundreds of people with the disease arrive there on early morning buses, before queuing at a nearby clinic for drugs. “They don’t want to be treated locally because they could lose their jobs, or their homes, but TB spreads in close quarters,” she said.

The involvement of people such as Gates has helped to spur investment, says the UK’s parliamentary office for science and technology, noting that there have been no new TB drugs for more than 50 years.

Today, 10 drugs, as distinct from vaccines, are in clinical trials. One of which, Bedaquiline, has already been cleared for use on patients who are suffering from drugs-resistant TB.

The number of drugs-resistant cases found in the UK has risen by half in the past decade. Treatment is more expensive and lasts considerably longer, while the drugs used “are unpleasant with significant side effects”, said Prof McHugh.

Each such case can cost up to £70,000 each – a manageable bill for the National Health Service. However, it is a cost that is entirely beyond the reach of health services in eastern and southern Europe, let alone those elsewhere.

Aids or HIV patients are particularly at risk and make up almost one in seven of all TB cases worldwide. They are 21 to 34 times more likely to develop infection from the mycobacterium tuberculosis bacterium.