For the first time an AIDS vaccine tested on more than 16,000 HIV-negative people in Thailand has shown that it could protect some of the volunteers from becoming infected. This caused a lot of excitement in the scientific community. All previous vaccine trials have failed to protect individuals from HIV. In fact, in one earlier vaccine trial, participants who received the vaccine were even more likely to become infected.
What made this vaccine different? And how effective was it? This vaccine, known as RV144, was a combination of two vaccines called Alvac and Aidsvax. Individually, these vaccines failed to protect people from HIV, but scientists had a hunch that if combined they might work better. When scientists did combine them and tested them in a group of people from Thailand, they found that the vaccine prevented three out of every 10 people from becoming infected with HIV. Scientists now think that combining the two vaccines stimulated a particular immune response in the volunteers that allowed some of them to not get infected. Blood samples from those individuals will now be studied with the hope of creating even more powerful vaccines that might protect even more people from becoming infected.
What does this HIV vaccine mean to those that are already HIV infected? This vaccine was designed to protect HIV-negative individuals from becoming infected. For those who are already infected, this vaccine will not likely have any benefit. In fact, vaccinated patients who still contracted HIV had the same level of virus in their blood as patients who never received the vaccines. What this suggests is that the vaccine may not have any benefit in helping people who are already HIV-infected.
As promising as this finding is, we still don't know the exact recipe for why this vaccine worked in some people but not in others. Right now scientists are looking at the blood samples of people in this trial to determine the important immune responses that protected some individuals. It's definitely a good starting point but we're still about 10 years away from an effective HIV vaccine.
This news is very promising, but we still need to keep up with our prevention efforts. Currently in the United States, there are 56,000 new HIV infections every year; that's one new infection roughly every eight minutes. We can't afford to wait for a vaccine. So in the meantime, we need to continue with our current prevention efforts (for example, encouraging condom use and funding for needle-exchange programs) as well as to look to new scientific strategies like preexposure prophylaxis while waiting for a truly effective vaccine to arrive.
Urbina is an HIV specialist and the medical director of HIV education and training at St. Vincent's Comprehensive HIV Center as well as an associate professor of medicine and an associate professor of clinical public health at New York Medical College. He also serves on the President's Advisory Council on HIV/AIDS.
