HIV is a virus that is incredibly tough to nail down. It mutates constantly - not enough to lose its deadly aspects, but enough to shapeshift, as it were, preventing our immune systems from recognizing it. That makes a vaccine really difficult to create.
But now the New York Times is reporting that a new combination of experimental vaccines appears to be effective in lowering the risk of HIV infection! In a controlled study, the number of people in a group using the vaccine had 30% fewer HIV cases compared to a group who did not get vaccinated. Specifically, there were 51 HIV cases out of 8200 people vaccinated versus 74 out of 8200 not vaccinated. That's very heartening! The vaccination course is actually composed of two different vaccines, neither of which on its own was effective, but together appear to boost the immune system enough (in some cases) to help fight off the initial virus infection.
A few things to note:
1) The vaccine course was not 100% effective, and does not drop the viral load of someone already infected. This is a prophylaxis, a preventative. It's not a cure.
2) There is no HIV in the vaccine itself -- it has pieces of the protein HIV coats itself with, to help the body recognize the virus -- so people using it cannot get HIV from it.
3) The vaccine is not widely available; it's still experimental. It was also tested on just strains found in Thailand, which may not translate well for other strains found elsewhere.
4) The vaccination was developed by the U.S. Army in cooperation with the National Institute of Allergy and Infectious Diseases. Expect the antivax cranks to go ballistic over that first part.
I think this is a big stride forward, but as always there's a ways to go yet. Ask anyone in the medical profession what the most important advance in history has been in their field, and vaccines are very high on the list. Vaccines have saved hundreds of millions of lives... and it looks like scientists will continue to find ways to do so.
My thanks to Steve Novella for chatting with me about this.