大象传媒

Giving people cash in exchange for doing the right thing for their health is the latest trend. Mexico lead the way in paying people to look after their health with a system set up in 1997 called Opportunidades.

Mothers in five million households receive cash in exchange for tasks like attending pre and post natal check ups and making sure their children receive vaccinations and go to school. At least thirty other countries have since set up similar schemes.

In the past few years in the UK, National Health Service funded schemes have sprung up, offering financial incentives in the form of shopping vouchers to encourage people to be more healthy.

The schemes target a whole range of behaviours, from quitting smoking and eating less to getting teenagers to turn up for the course of vaccinations against the human papilloma virus that causes cervical cancer.

But does paying people to be healthy work? Claudia Hammond assesses the evidence and makes a discovery that astonishes her.

In one completely unexpected area of healthcare - drug addiction - shopping vouchers are proving to be not only effective, but cost effective too.

This is a highly controversial scheme. Many people in the UK are uncomfortable with the idea that drug addicts should be paid to give up crack. Director of the National Addiction Centre, Professor John Strang, disagrees. When it comes to addiction, 'it's bordering on negligent not to be willing to do that'.