Christina Scott -21 September 2007 SciDev.Net

Africa's biggest HIV vaccine trial were stopped today (21 September) after a sister study testing the same experimental vaccine in US men found no protection against infection.

Glenda Gray, from the Chris Hani Baragwanath Hospital in Johannesburg, South Africa, and a lead researcher with the Phambili vaccine trials, confirmed that 700 volunteers from five sites in South Africa had already begun a series of three injections spaced over 12 weeks.

''Not one volunteer has been put at risk or harmed in any way,'' she emphasised.

The South African tests, intended to recruit 3000 people, have been ''paused'' until local researchers have studied the American data, based on men who have sex with men.

''This is a good sign in a way,'' Gray told SciDev.Net. ''This virus is elusive. We learn from these setbacks. We learn new ways, new ideas about to find a vaccine. We change our strategies as we learn more."

But Gray also said the stoppage was ''a tragedy which has put us back twenty years''.