One of the most remarkable achievements of medical science in my lifetime has been the treatment of Aids. In the final decades of the last millennium, contracting HIV was a death sentence. Victims would be lucky to survive ten years after infection. The virus, which seemed a cruel punishment for intimacy, terrified a generation. Then the science kicked in.

In 1996, antiretroviral drugs were developed that slowed the condition’s progress. Steadily, the therapy was enhanced and improved. Today, sufferers can expect to lead a full life. Research by the University of Bristol found that a 20-year-old starting treatment can now live to 67.

But there’s a catch. Progress like that does not come cheap. The lifetime cost for treating one HIV-infected individual averages about £300,000.