The team of British and American experts said that the WHO’s level of failure could have been “catastrophic” had it been dealing with a more severe disease.
The Ebola epidemic started in Guinea in West Africa in late 2013.
Since then, 28,000 people have been infected and 11,000 have died of the disease.
While death and infection rates have slowed greatly, health officials in Liberia today confirmed three new cases more than two months after the country was declared free of the deadly disease for the second time.
“The failures of WHO in this disease outbreak were several,” said Professor Ashish Jha, one of the authors of the report and a director of the Harvard Global Health Institute.
“One was that it was very, very slow to respond.
“WHO has a very specific responsibility, which is declaring what is called a public health emergency of international consequence.
“It didn’t do that until August of 2014, a good eight months after the disease had started spreading and many, many months after others had said this disease is getting out of control. And even after it declared it, its response was not as effective as it should’ve been.
“So really the failures were a slow response, an ineffective response requiring a lot of other countries to step in and help.”
Professor Jha said that if Ebola had been a more contagious or dangerous disease, this inadequate response would have been greatly magnified.
“Could’ve been catastrophic, could’ve been catastrophic,” he said.
“Now you could argue that 11,000 people dying unnecessarily is catastrophic. It could’ve been much much worse.
“So I think of this as a wake up call, to say we have to do better.”
He said the crisis had broader implications for how all health crises were dealt with by authorities.
“This crisis I think revealed flaws in how we think about disease outbreaks, really at all levels, from individual countries to the international organisations.
“And the consequence is that 11,000 people in West Africa died that really should not have died, and of course there were effects throughout the world.”
Dr Grant Hill-Cawthorne, a senior lecturer in Communicable Disease Epidemiology at Sydney University, said the report was a fair assessment of the inadequate global Ebola response.
“I think it’s a failure of multiple countries put together, not just the WHO,” he said.
“I think one of the key aspects here is the importance of strengthening the domestic governments so that they can actually have the capacity to, one, run surveillance within their countries to be able to identify if these infections have appeared, but also have basic ways of being able to track them and also respond to them.
“And this has been something that’s been on the agenda for the last 10 years, has really been ignored up to now, and it’s only with the outbreak of Ebola and all of these deaths that finally the world is focusing on this.”
Dr Hill-Cawthorne said it should also be acknowledged that bodies like the WHO were hindered by the governments and people of the nations they were trying to help.
“These are certainly countries where not just the population but also the politicians were quite nervous about outside influence,” he said.
“At least two of them were post-war countries, they’d been countries where their own governments had committed various atrocities at various points.
“And so merely trying to get the communities on board was hard. And when they saw people coming in in white suits, not really communicating with them what the problem was, and then seeing their loved ones dying and being buried without their knowledge, that all sparked a lot of concern and so there were certainly communication issues.”
‘We remain vulnerable’
The report makes 10 recommendations for improving systems to cope with future outbreaks.
Among them are calls for better funding and a global strategy to help poorer countries monitor and respond to infectious diseases.
The authors also recommend that a global fund be established for drug and vaccine research and development.
Professor Ashish Jha said the next epidemic could be just around the corner.
“This outbreak of Ebola, in some ways we got lucky,” he said.
“Eleven thousand people died unnecessarily but this is not a disease that spreads very easily or very quickly.
“If this had been a different disease, it could have been catastrophic and the truth is we remain vulnerable, and so we have to have a more effective international system for disease monitoring and disease prevention, otherwise we’re all at risk.”
The report was written by the Harvard Global Health Institute and the London School of Hygiene and Tropical Medicine, and published today in medical journal The Lancet.
The World Health Organization has been contacted by the ABC for comment.