South Africa\'s programme to prevent HIV in babies has achieved a 96.5 percent success rate in wiping out transmission from infected pregnant mothers, the Medical Research Council said Thursday. An inaugural national evaluation survey among the world\'s biggest AIDS population tested 9,915 infants at public clinics, of whom 31.4 percent were exposed to the virus but only 3.5 percent tested positive, the government research body said. \"This survey was the first-ever rigorous national... evaluation in the nine provinces of South Africa,\" said Ameena Goga of the MRC. Infection rates among mothers ranged from 15.6 percent in the sparsely populated Northern Cape to 43.9 percent in KwaZulu-Natal, which is the hardest hit region in the country. Babies aged between four and eight weeks between June and December last year were tested at 580 sites across South Africa. The study will be repeated this year and in 2012 to evaluate transmission rates over three years and the babies will be tracked up until they are 18 months old. Last year, South Africa introduced new anti-AIDS drugs guidelines that include treatment for mothers at an earlier stage of illness. The government was previously heavily criticised for refusing to roll out the life-saving drugs, but 1.4 million people are now on treatment. The virus infects 5.6 million of the 50-million population, according to UN estimates.