Billions of private, charity and government-sourced dollars have been spent during the past two decades searching for an effective HIV vaccine. Now there is something to show. France’s Sanofi-Aventis, in partnership with two US biotechnology companies, this week said an experimental vaccine appeared to reduce the rate of HIV infection by 31 per cent.

Certainly worth celebrating, given that HIV/Aids kills more than 2m people each year. Yet this is just a jab in a big fight. The study’s small size and the vaccine’s relatively low effectiveness mean much more work is required before a widely available HIV vaccine becomes reality.