Three decades of attempts to create a vaccine against HIV have been fruitless. The virus has a high mutation rate, which helps it adapt to evade both natural immune systems and artificial vaccines.

But there may be a new hope.

Moderna, an American firm that found fame by quickly coming up with a viable covid-19 jab, is planning human trials of a novel vaccine against HIV.

Its researchers hope the same mRNA technology will succeed against HIV too, by creating a vaccine which the virus cannot easily dodge.