While a successful trial of the RV 144 HIV vaccine is a major step forward in HIV/AIDS research, experts say that the vaccine’s efficacy provides few answers but raises many questions, aidsmap.com reports. In a Thailand-based trial—the largest ever staged for an HIV vaccine—RV 144 reduced the risk of HIV infection by more than 30 percent in participants.

“This trial poses fundamental ‘black box’ questions,” said Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), which funded the trial alongside the Thai Ministry of Public Health, the United States Army and patent-holders to the two parts of the vaccine, Sanofi-Pasteur and Global Solutions for Infectious Diseases. 

He continued, “What are the correlates of HIV immunity? Has this trial overturned our understanding of what might constitute a protective response to HIV? Can we improve on this efficacy? And does this result mean we should refocus more on clinical research than basic science? Not at all. NIAID’s commitment to keeping an appropriate balance between basic science and vaccinology versus empirical clinical trials has not changed.”

According to the article, some scientists viewed the RV 144 trial as a waste of money given its $105 million price tag.

“We did hesitate to continue the trial because of the criticism from the scientific point of view,” said principal investigator Supachai Rerks-Ngarm, MD. “But in view of the need for an HIV vaccine, and in consultation with many international experts, we decided to move forward. That determination turned out to be very significant.”