In a letter published in the journal Nature, scientists report that in 13 HIV-infected people who discontinued their cocktail of retroviral drugs, infusions of a neutralizing antibody called 3BNC117 staved off the expected rebound of the human immunodeficiency virus for more than a month.

Typically, when an HIV-infected patient stops taking his or her anti-retroviral medications, the virus bounces back to dangerous levels within 18 days. But in findings reported Wednesday, scientists wrote that all of the 13 participants saw their viral loads suppressed to very low levels for at least five weeks after their last treatment — delaying resurgence of the virus twice as long as normal.

Six of the 13 participants saw their viral loads suppressed to very low levels for at least nine weeks after their last treatment — three times the normal span.