Some people say that smokers deserve a shot in the head, but an experimental vaccine may one day make it possible to give them a shot in the arm to get them to quit. A study found that more than twice as many people given five of the shots stopped smoking than those given fewer or phony shots - about 15 percent versus 6 percent after one year. That’s comparable to some other smoking cessation aids currently sold, the Associated Press reports.

The results, presented at the American Heart Association conference, don’t prove the new approach works but encouraged some experts. “It clearly shows promise” and merits a definitive study, says Frank Vocci, director of medications development at the National Institute on Drug Abuse, which has given $8 million for the research so far. “There’s merit in it,” but it won’t be available tomorrow, the lead researcher, Stephen Rennard of the University of Nebraska, tells the AP.

The study tested NicVAX, a vaccine designed to “immunize” smokers against the rush fueling their addiction. The shot, which is made by Nabi Biopharmaceuticals, keeps nicotine from reaching the brain, taking the fun out of smoking and hopefully making it easier to give up. This approach - attacking dependency in the brain - is different than just replacing nicotine, as the gum, lozenges, patches and nasal sprays do, the AP writes.

The study involved 301 longtime smokers in and participants were given four or five shots within six months, at one of two doses, or dummy shots. Neither they nor their doctors knew who got what. Initial shots “prime” the immune system. Later doses make it produce antibodies, which latch onto nicotine in the bloodstream and keep it from crossing the blood-brain barrier and maintaining the addiction.

One year into the study - six months after volunteers received the last shot - 14 percent on the lower dose and 16 percent on the higher dose of five shots had quit. Only 6 percent of those given four shots, or the fake vaccine, were off cigarettes. “These quit rates are comparable to what’s seen in other studies for things that are considered to work,” Rennard says. More people in the vaccine groups dropped out of the study - 74 out of 201 versus 33 of the 100 in the placebo group. Two vaccine recipients had minor side effects, Rennard reports.

“These are impressive preliminary data,” says Sidney Smith Jr., a cardiologist at the University of North Carolina at Chapel Hill and past heart association president. Getting people to quit smoking “may well be at the top of the list” for improving public health, he adds. Worldwide, an estimated 1.3 billion people smoke, according to the heart association and it’s a leading cause of cancer and heart disease.

Others were not as impressed. “I’m a little underwhelmed,” says Timothy Gardner, a heart association spokesman and cardiologist at Christiana Care Health System in Newark, Del. “I would think we could expect better” with such a novel approach, and it is hard to understand why five shots worked and four did not, he notes.

The FDA granted the vaccine fast-track status, meaning it will get prompt review. Two similar vaccines are in midstage testing: TA-Nic, by Celtic Pharmaceuticals, and NicQb, a product whose marketing rights Cytos Biotechnology recently sold to Novartis.

A similar “brain approach” to smoking cessation is taken by Pfizer’s Chantix, a drug that went on sale in August 2006. In a study, researchers reported one-year smoking abstinence rates of 22 percent versus 16 percent of those given the smoking cessation drug Zyban.

Of the roughly 46 million smokers in the United States, 40 percent each year make a serious attempt to quit, but fewer than 5 percent succeed long-term. With the vaccine, people who have not quit may require periodic boosters to keep trying, according to Vocci.