Doctors in the U.S. have made medical history by effectively curing a child for the first time ever of HIV.

The infant was born with HIV, but he's now two and a half years old...and HIV free. He was once on medication to reverse the HIV, but he's now been removed from all medicine, has a normal life expectancy and is highly unlikely to be infectious to others.

Though medical staff and scientists are unclear about why the treatment was effective, the surprise success has raised hopes that the therapy might ultimately help doctors eradicate the virus among newborns.

Doctors did not release the name or sex of the child to protect the patient's identity, but said the infant was born, and lived, in Mississippi state. Dr. Hannah Gay, who cared for the child at the University of Mississippi medical centre, told the Guardian the case amounted to the first 'functional cure' of an HIV-infected child. A patient is functionally cured of HIV when standard tests are negative for the virus, but it is likely that a tiny amount remains in their body. "Now, after at least one year of taking no medicine, this child's blood remains free of virus even on the most sensitive tests available," Gay said.