Scientists forced to cut safety corners in race to create Ebola vaccine

Normally it takes years to prove a new vaccine is both safe and effective before it can be used in the field. But with hundreds of people dying a day in the worst-ever outbreak of Ebola, there is no time to wait.

In an effort to save lives, health authorities are determined to roll out potential vaccines within months, dispensing with some of the usual testing and raising unprecedented ethical and practical questions.

"Nobody knows yet how we will do it. There are lots of tough real-world deployment issues and nobody has the full answers yet," said Adrian Hill, who is conducting safety trials on healthy volunteers with an experimental Ebola shot developed by GlaxoSmithKline (GSK).

Hill, a professor and director at the Jenner Institute at Britain's University of Oxford, said that if his results showed no adverse side effects, GSK's new shot could used in people in West Africa by the end of this year.

Even if a drug is shown to be safe, it takes longer to prove it is effective - time that is simply not available when cases of Ebola infection are doubling every few weeks and are projected by the World Health Organisation to reach 20,000 by next month. More than 3,500 sufferers have died already.

Among questions that scientists are grappling with: Should an unproven vaccine be given to everybody, or just a few? Should it be offered to health-care workers first? The young before the old? Should it be used first in Liberia where Ebola is spreading fastest, or Guinea where it is closer to being under control?