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Just the shot - or not
November 23, 2006
Experts are warning that vaccines against nicotine and illicit drugs such as cocaine may not be the panacea they appear to be. Ruth Pollard reports.
IT SOUNDS like the ultimate solution to one of the world's leading causes of preventable death and disability. So why are public health experts sceptical?
The race is on to produce the first vaccine against nicotine addiction, with three biotech companies already well into clinical trials in Britain, Europe and the United States.
Vaccines are intended to help smokers quit by inducing the immune system to produce antibodies that bind to nicotine and prevent it crossing the blood-brain barrier to act on receptors in the brain.
That is, they stop the pleasurable sensation smokers receive when nicotine reaches the brain.
But there are many ethical concerns about the vaccines, and others in the pipeline for addictions to illicit drugs such as cocaine, leading experts to warn they may not be the panacea they appear to be.
"Nicotine vaccines are no magic bullets and we should be extremely wary of going down the path of using them preventively," says Wayne Hall, a professor of public health policy in the School of Population Health at the University of Queensland.
He says there are real concerns that parents, keen to prevent their children from taking up smoking, will expect doctors to give the vaccine off-label to adolescents.
The vaccines under development provide a limited period of protection - no more than six months - so children would require booster injections throughout adolescence, possibly once every two or three months, if they were to remain protected, he says.
Then there is the danger that teenagers may rebel against parental control and smoke cigarettes with a higher nicotine content than the vaccine, thus rendering it useless.
"The vaccines that people are developing now are primarily intended to get smokers through those three to four months after they quit … if they do slip up and start smoking again, they will not get much of a buzz," Hall says.
"That is a different situation to giving a vaccine to somebody who is 12 or 13 years old to stop them taking it up by the age of 18."
Successful phase one trial results have been completed on one of the vaccines and phase two human clinical trials are in progress on all three vaccines, but none has been tested for its safety or effectiveness in young people.
Early reports of abstinence rates at six months released by researchers looked promising, perhaps doubling the success rate of existing drugs such as Zyban or nicotine replacement therapies, Hall says. "Evidence from the early studies suggests that it does really substantially improve on nicotine gum and patches."
Other experts in tobacco control, such as Simon Chapman, despair at the focus on costly, quick-fix pharmaceutical solutions at the expense of proven public health interventions such as counselling and support.
Chapman, a professor of public health at the University of Sydney, cites the last anti-smoking drug to come on the market, Zyban.
"Nearly one in 10 Australian smokers were prescribed this drug at a cost of millions and millions of dollars on the Pharmaceutical Benefits Scheme, and there was no [significant] fall in smoking rates," he says. "It presents a view that the control of smoking must rest in the consumption of a commodity - in this case a vaccine - with its huge unknowns and huge costs."
He, too, is concerned that parents might force their children to have the vaccine, at a time when, at 8.4 per cent, the smoking rate in teenagers has never been lower, pushed down by concerted campaigns to "denormalise" smoking.
"Policymakers can sometimes get enormously excited about the promise of futuristic approaches, which are seen as innovative, but if we just keep doing what we are doing, tobacco consumption will continue to be in free-fall," he says.
"You don't have to look too far for the influence of the pharmaceutical industry fanning the enthusiasm for this in scientific circles."
About 1.3 million people in NSW regularly smoke, translating into about 4 million Australians, or 20 per cent of the adult population - a figure that has been steadily decreasing over the past decade.
Each day 150 people are admitted to hospital in NSW with smoking-related illnesses, representing $1.7 billion a year in direct health costs and $6.7 billion in indirect costs, such as lost work days and carers' costs.
Half of all smokers in Australia will die of a smoking-related illness and one-third will die in middle age, losing an average of 22 years of life, says the state's chief cancer officer, Jim Bishop.
But as soon as a smoker quits the habit, the risk of heart attack and stroke drops immediately and there are other significant health benefits.
Bishop describes as promising the early results from the most advanced vaccine, with indications up to 40 per cent of participants had been able to quit smoking during one of the trials.
"We know that two-thirds of smokers want to quit … the reason they don't quit is because of nicotine addiction, yet with this vaccine, the person would not have any reason to smoke because they are not getting a rush.
"We are in favour of anything that can be proven to get people off cigarettes - the one thing we would like to know is how long the effect would last and whether you would need boosters."
Along with the vaccines under development for nicotine, researchers are working on a vaccine for cocaine addiction that works in a similar way, preventing antibodies from crossing the blood-brain barrier.
Cocaine is one of the most widely used illicit drugs in the world and as many as one in six users becomes dependent on the drug, resulting in anxiety disorders, fatal cardiac arrests, seizures and higher rates of risky sexual and drug-taking behaviour.
Hall says that the most promising application of a cocaine vaccine has been to prevent abstinent users from relapsing.
But there are serious ethical concerns over whether the vaccine could be forced on people via the legal system without due regard for the potential side effects or other issues playing out in a drug user's life.
"It will be presented as a free choice, but effectively it will be 'take this vaccine or stay in jail'," warns Alex Wodak, the director of drug and alcohol services at St Vincent's Hospital in Darlinghurst.
And what may seem like the perfect solution for anxious parents worried about their troubled children, or a society anxious to stamp out the chaos and crime associated with drug addiction, could be nothing more than a quick fix.
"Often people are taking drugs because of very difficult problems in their life, childhood sexual or physical abuse, generations of conflict in their families, or other real, significant problems that people have to contend with.
"These are people with not a lot of inner resources, not a lot of money, poor housing, they are stuck in a situation they cannot get out of - drugs are often seen as a solution."
Wodak is keen to see the range of treatment options for addiction to drugs and alcohol expanded, and says pharmaceutical tools are key to broadening these horizons.
But he says good research in this area has been done only in recent times, and past pharmaceutical treatments that have been lauded as cures - such as naltrexone - had not delivered.
KICKING THE HABIT
There are a number of techniques to quit smoking, with varying rates of success.
No intervention - 4 per cent succeed
Brief advice - 6 per cent succeed
Telephone counselling - 9 per cent succeed
Nicotine replacement therapy (patches or gum) plus counselling - 17 per cent succeed
Nicotine replacement therapy plus sustained counselling - 27 per cent succeed
Zyban plus counselling - 32 per cent
Vaccine trials report up to 40 per cent success
SOURCE: AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH
Sydney Morning Herald
