Researchers have ended the latest effort to find an HIV vaccine after a review last month determined that the experimental injections did not provide protection from the virus that causes AIDS. The $120 million study, conducted by the HIV Vaccine Trials Network (HVTN) based at Seattle’s Fred Hutchinson Cancer Research Center, was launched more than three years ago. It involved 5,407 volunteers in South Africa, making it the largest ongoing clinical trial in the decades-long search for an HIV vaccine. “There was great hope and expectations around this vaccine candidate,” said Mitchell Warren, executive director of AVAC, a global HIV prevention organization. “It’s incredibly disappointing.” Initial results of the vaccine showed that it prompted a strong immune response, but a review by an independent monitoring board last month found that it wasn’t effective in preventing infection.

“We’ll learn from this, but we need to press on,” said Dr. Larry Corey, former president of Fred Hutch. While there is still no cure for HIV, antiretroviral drugs have been used to treat the disease, which has significantly lowered the virus’ death rate around the world. HIV has reportedly killed more than 32 million people since the early 1980s. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, said an HIV vaccine “is essential to end the global pandemic.”