Last month, the U. S. army and Thai researchers announced the path-breaking production of a combination vaccine which caused a statistically important 31% reduction in new HIV infections in a trial of more than 18,000 volunteers in Thailand.

The first vaccine results rose hopes for the production of a vaccine against the deadly infection which has killed more than 25 million people worldwide.

The researchers decided to go ahead and announce this advancement publicly in a news conference rather than waiting for the formal publication of their findings, though the complete results have not been made public.

However, after the secondary analysis the researchers found out that the vaccine has not turned out to be as promising as was expected reducing infections 24% which is not statistically significant.

The secondary analysis which was part of the protocol and is considered normal for all vaccine trials excluded patients who did not follow the experimental procedure. The results were less impressive after this was done.

This study was greatly criticized at its launch three years ago since every component of the combination vaccine had failed in previous trails. Nevertheless, the National Institute of Allergy and Infectious Diseases hoped that it would throw light on the kinds of biological responses that must be provoked by a vaccine for it to provide immunity.

The researchers have been criticized eventually for the way they chose to release the study results but they clarified their act by saying that they feared that the results will be leaked before they presented them therefore they preempted such an event.