The world’s 1.3 billion smokers could eventually have a powerful new way to kick the habit – a vaccine against nicotine.

Nearly 60 per cent of smokers who achieved high levels of antibodies against nicotine after receiving the vaccine stopped smoking for at least six months, according to a study at the American Society of Clinical Oncology in Orlando, Florida.

According to Dr Cornuz, who led the study, “The data suggests that antibodies against nicotine are effective in helping people quit smoking.”

About a third of those who received the vaccine achieved the highest levels of antibodies.

But before the vaccine is put through larger clinical trials, Cornuz said, it will have to find ways “to intensify the immunisation scheme” so that more people achieve the necessary antibody levels.

That may mean more injections, or higher levels of the immunising agent in each dose. He estimated it would be as long as three years before new trials could begin.

Smoking is thought to be the cause of 30 per cent of all cancer deaths and 87 per cent of deaths from lung cancer.

At least four companies are testing nicotine vaccines: Cytos Biotechnology (Zurich), whose vaccine Cornuz studied, Xenova Group of Berkshire (England), Nabi Biopharmaceuticals (Florida), and Prommune (Omaha).

The concept behind the vaccines is simple. Antibodies to nicotine bind to it in the blood and remove it, preventing the drug from reaching and stimulating the brain.

“We’re taking away the positive reinforcement, which is the main reason people can’t stop smoking,” said Dr Henrik S Rasmussen, a senior vice president of Nabi.

In the current trial, the researchers enrolled 341 patients. Two-thirds of them were given the experimental vaccine in five doses over a four-month period. The rest were given a placebo.

Of the 53 patients who developed the highest levels of antibodies, 30 stopped smoking, and those who didn’t , smoked fewer cigarettes, Cornuz said.

Researchers relied on subjects’ reports of smoking and on measurements of carbon monoxide levels in the blood, a conventional measure of smoking.

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