Mexico’s government said a “vaccine” against heroin addiction, which it patented this week, will be ready for human use in roughly five years.

During a working visit to the northern border city of Ciudad Juarez, Health Secretary Salomon Chertorivski said all the laboratory experiments have already been carried out on rats and “the next step is testing on humans.”

The vaccine 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, Chertorivski told reporters Friday.