HIV vaccine fails in experimental study

A US-backed study of an experimental HIV vaccine has suddenly ended after volunteers who received the vaccine contracted HIV.  The study had enrolled 2,504 volunteers across the United States and divided them into two groups. One group received the HIV vaccine, while the other was injected with a placebo. But researchers made a disturbing finding: out of the group who received the vaccine, 41 developed HIV, while in the group that received the placebo there were just 30 HIV cases. 

In a statement, the National Institutes of Health says  that such a discrepancy is "non-statistically significant," though the NIH adds that "it is not clear why this occurred and further analysis is needed to draw any firm conclusions."

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While the study has ended, the NIH promises to continue monitoring the health of the volunteers who participated for the next five years.

The trial had been going on since 2009. It is just one of many failed HIV vaccine trials. Yet health advocates remain optimistic. 

"This trial has provided a clear, swift answer about a specific vaccine strategy. It's not the answer we hoped for, but the search doesn't end here," Mitchell Warren, executive director of the nonprofit group AVAC: Global Advocacy for HIV Prevention, said in a statement to Reuters. "Researchers need to unpack the data from this trial to understand more about why this strategy didn't prevent infection."