How did it happen?
The ten-year-old child caught the infection from the mother around time of birth.
South African doctors claim the child, whose identity is being protected, was given a burst of treatment shortly after birth.
Since then, the child has been off drugs for eight-and-a-half years without symptoms or signs of active virus.
In contrast, most people need treatment every day to prevent HIV from destroying the immune system, resulting in AIDS.
Therefore, understanding how the child is protected could lead to new drugs or a vaccine for stopping HIV.
Early anti-retroviral therapy was not standard practice in 2007 when the child was born, but was given to the child from nine weeks old as part of a clinical trial.
After 40 weeks, when levels of the virus became undetectable, treatment was stopped. But unlike anybody else on the study, the virus has not returned.
