In Mexico, a vaccine against heroin addiction has been patented and will
be ready for human use in next few years, say sources.
Health Secretary Salomon Chertorivski said laboratory experiments have been carried out on rats and "the next step is testing on humans".
The vaccine, however, must undergo a "normal development process" and therefore at least another five years of work will be required before it can be used by human beings, he said.
"And it's not only heroin... that's what's been patented so far but we're advancing rapidly on cocaine and methamphetamines," he said.