“This is really the first step toward HIV remission and a cure,” said Deborah Persaud, a virologist at Johns Hopkins Children’s Center in Baltimore. “Understanding the factors that came into play to lead to this outcome is really going to inform science.”

Out of the millions of children worldwide who are HIV-positive, the child, now 9, is one of only three who have been identified by scientists as having the ability to stop the virus from resurging for an extended period of time.

Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, struck notes of both optimism and caution when speaking about him. Fauci described the child as being in “remission” rather than being cured. And while hoping that the child would never have an active infection, Fauci noted that HIV tends to hide in “funny places” and that it is “not entirely inconceivable” a small amount of the virus may remain in the body and start replicating again.