AN experimental vaccine against cocaine [...].

AN experimental vaccine against cocaine addiction could be used to wean users off the drug, research has shown. In a US trial of the vaccine, around 40% of treated individuals were protected, but only for two months. Many stopped taking cocaine or reduced their consumption after having the jab.

Previous research has shown that immune system antibodies can deactivate cocaine before the drug enters the brain. The new 24-week study involved 115 cocaine-dependent addicts, 58 of whom were randomly assigned to receive five vaccination jabs over three months.

The other participants received "dummy" placebo injections. Random tests were carried out for signs of cocaine in the addicts' urine.

Of the 55 participants who completed the course of active treatment, 38% attained high enough blood antibody levels to combat cocaine dependency. Urine tests between weeks nine and 16 of the study indicated that 45% of this group had stopped taking cocaine, compared with 35% of those given the placebo.

The proportion of participants who reduced their cocaine use by half was significantly greater among those successfully treated with the active vaccine. The research, led by Dr Bridget Martell, from the Yale University School of Medicine in New Haven, Connecticut, is reported in the journal Archives of General Psychiatry. The authors wrote: "Optimal treatment will likely require repeated booster vaccinations to maintain appropriate antibody levels."