Drop in Ebola cases may thwart drug and vaccine trials

http://www.newscientist.com/article/dn26951-drop-in-ebola-cases-may-thwart-drug-and-vaccine-trials.html#.VVpxC_AYFB8

Debora MacKenzie
Feb. 11, 2015

We may have lost a historic chance to test drugs and vaccines against the Ebola virus, which could leave us without the weapons to prevent the next outbreak.

The epidemic in West Africa prompted an unprecedented rush of clinical trials. But some are now being abandoned and others may produce few clear results, because the steep fall in the number of Ebola cases makes it difficult to test whether the drugs work in enough people for the trials to be statistically valid.

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No one is complaining that last year's exponential rise in Ebola cases did not continue. David Fisman of the University of Toronto, Canada, says something slowed disease transmission in November, possibly ordinary people taking more precautions. Factoring that into epidemic models "nicely predicts" what is happening now, he says. "We think the epidemic is peaking now, or peaked in mid-January. We project around 35,000 reported cases in total" – far short of the million feared in September.

But there is a downside. It has never been possible to test treatments for Ebola in humans as outbreaks were small and over too fast. This time, clinical trials have begun, but may not be completed because of the decrease in cases.

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The irony of defeating Ebola just in time to prevent tests that could stop the next epidemic is not lost on researchers. The trials were designed and approved in months rather than the years it usually takes – but that's still not soon enough, says Jake Dunning of Imperial College London, who hopes to launch a trial of an RNA-based anti-Ebola drug in Sierra Leone next week.

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