Ebola vaccine trial shows 100 per cent efficacy: WHO

The world is on the verge of an effective Ebola vaccine that has shown a 100 per cent efficacy in phase three clinical trials, the WHO said today.
"We believe that the world is on the verge of an efficacious Ebola vaccine," said Dr Marie-Paule Kieny, Assistant Director General of the WHO.
The results from an interim analysis of the Phase III efficacy vaccine trials in Guinea show that VSV-EBOV, also known as the Canadian vaccine, is highly effective against Ebola.
"While the vaccine up to now shows 100 per cent efficacy in individuals, more conclusive evidence is needed on its capacity to protect populations through what is called 'herd immunity'," said the WHO.

The vaccine was originally developed by Canadian public health agencies but the rights to market and distribute it is now with Merck & Co, Inc.
More than 11,200 people have died in an Ebola epidemic in west Africa that began in late 2013 in Guinea and then spread to Liberia and Sierra Leone, infecting 27,700 people in the worst outbreak on record.

"Our approach for the design of clinical trials has been to vaccinate contacts and contacts of these contacts in recently identified Ebola patients," Dr Kieny said.
"The strategy of the vaccination is to create a ring of protection around the infected person," she said.

The clinical trials that were sponsored by the WHO, a rare thing for the WHO to do, used the ring vaccination trial method--where rings are defined, the rings are then randomised and then some rings are vaccinated immediately and some rings are vaccinated after three weeks-was used to test the efficacy of the vaccine.
The transmission of the virus stopped where the population was injected with the vaccine immediately.
"Prior to vaccination there were cases, cases, cases, (when) the vaccination arrived, ten days after, (there were) no cases. Flat. Whether this is protection or not everybody can judge for themselves. It could be a game changer because previously there was nothing against Ebola inspite of this disease being identified 40 years ago," Kieny said.

The Guinean trials which began on March 23 this year to understand the efficacy and the effectiveness of a single dose of VSV-EBOV, shows that none of the 2014 people who were exposed and vaccinated developed Ebola after ten days.
On the other hand, out of the 2380 who constitute the control group, 16 developed Ebola virus disease.