Why Do HIV Vaccine Trials Keep Failing?
Spending hundreds of millions of dollars to manufacture and test HIV vaccines that have little reasonable hope of efficacy is wasteful, at best. More comprehensive basic and preclinical research would enable scientists to identify approaches with a far better chance of success – and at much lower cost.
DURBAN – Yet another seemingly promising HIV vaccine has failed in clinical trials. According to Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases at the United States National Institutes of Health, which was conducting the trial, a vaccine is “essential to end the global pandemic.” But while the latest failure is a disappointment, it should come as no surprise.
To understand why, it is useful to go back to the beginning. Just over 12 years ago, two studies involving a vaccine candidate known as MRK-Ad5 were halted. The failure was comprehensive: the studies – STEP (which enrolled men and women in the Americas, the Caribbean, and Australia) and Phambili (including men and women in South Africa) – found that MRK-Ad5 failed to protect subjects against HIV infection. Worse, there was evidence that it may have increased the chances of acquiring HIV, the virus that causes AIDS.
The next year, however, hopes were again raised, as another clinical trial – known as RV 144 – seemed to show modest positive results in Thailand. Yet the conclusion that the vaccine worked was based on somewhat dubious statistical analysis.