Scientists in the US believe they have managed to cure an infant of HIV.

The child from Mississippi is now aged two-and-a-half. She was born to a HIV-positive mother and began receiving antiretroviral therapy (ART) within 30 hours of her birth.

The scientists believe this may be key as the prompt administration of the drugs may have stopped the formation of viral reservoirs. These are dormant cells that are notoriously difficult to treat. They are responsible for reigniting the HIV infection in most patients within weeks of stopping therapy.

"Prompt antiviral therapy in newborns that begins within days of exposure may help infants clear the virus and achieve long-term remission without lifelong treatment by preventing such viral hideouts from forming in the first place," explained lead scientist, Dr Deborah Persaud, of the John Hopkins Children's Center.

She believes this is what happened with this child, who has now been declared ‘functionally cured'. A functional cure refers to a patient who achieves and maintains long-term viral remission without lifelong treatment. The viral presence is so low, standard clinical tests cannot detect it.

Currently, babies at high risk of having HIV receive a combination of antiviral drugs at prophylactic (preventive) doses for six weeks. They do not start therapeutic doses until HIV is confirmed.

In the case of this child, a series of tests showed a progressively diminishing viral presence in her blood. Twenty-nine days after her birth, the virus was undetectable.

The child remained on antivirals until she was 18 months old, at which point she stopped attending hospital. It Is unclear why. Ten months later, the child re-entered the hospital system where she underwent repeated standard blood tests. The HIV virus was not detected in her blood.

She then underwent tests for HIV-specific antibodies - this is the standard clinical indicator of HIV infection - these were also negative.

"Our next step is to find out if this is a highly unusual response to very early antiretroviral therapy or something we can actually replicate in other high-risk newborns.

"Complete viral eradication on a large scale is our long-term goal, but for now, remains out of reach, and our best chance may come from aggressive, timely and precisely targeted use of antiviral therapies in high-risk newborns as a way to achieve functional cure," Dr Persaud said.

These findings were presented at the 20th Conference on Retroviruses and Opportunistic Infections in Atlanta.