The Ebola epidemic in West Africa could infect more than 20,000 people, the UN health agency said yesterday, warning that an international effort costing almost half a billion dollars is needed to overcome the outbreak.

As the World Health Organisation (WHO) announced its strategic plan for combatting the virus, GlaxoSmithKline said an experimental Ebola vaccine is being fast-tracked into human studies and it plans to produce up to 10,000 doses for emergency deployment if the results are good.

The WHO estimates it will take six to nine months to halt the Ebola epidemic in West Africa, while Nigeria said yesterday that a doctor indirectly linked to the Liberian-American who brought the disease to the country had died in Port Harcourt, Africa’s largest energy hub.

So far 3,069 cases have been reported in the outbreak but the WHO said the actual number in Guinea, Sierra Leone, Liberia and Nigeria could already be two to four times higher.

“This is not a West Africa issue. This is a global health security issue,” Bruce Aylward, the WHO’s Assistant Director-General for Polio, Emergencies and Country Collaboration, told reporters in Geneva.

This is not a West Africa issue, this is a global health security issue

With a fatality rate of 52 per cent, the death toll stood at 1,552 as of August 26. That is nearly as high as the total from all recorded outbreaks since Ebola was discovered in what is now Democratic Republic of Congo in 1976. The figures do not include deaths from a separate Ebola outbreak announced at the weekend in Congo, which has been identified as a different strain of the virus.

Aylward said tackling the epidemic would cost an estimated $490 million, involving thousands of local staff and 750 international experts.

“It is a big operation. We are talking [about] well over 12,000 people operating over multiple geographies and high-risk circumstances. It is an expensive operation,” he said.

The operation marks a major ramping up of the response by the WHO, which had been accused by some aid agencies of reacting too slowly to the outbreak.