LONDON – The scale of the current outbreak of Ebola presents a change in the development landscape for therapeutics, with a far greater demand for drugs than is realized, according to new epidemiological research.

While the World Health Organization (WHO) has acknowledged the existing stocks of experimental drugs that could potentially be used to treat Ebola are insufficient to meet the size of the outbreak, the question of by how much supplies need to be boosted was left hanging.

Now, scientists at Oxford University, who have attempted to estimate which kind and what volume of treatments are needed, said the demand is likely to be higher than many people realize. "Our analysis suggests that even under a conservative scenario, up to 30,000 people would so far have required treatment or prophylactics in the current outbreak," said epidemiologist Oliver Brady, writing in the Aug. 21, 2014, issue of Nature.

Brady and colleagues in Oxford University's Spatial Ecology and Epidemiology Group, who specialize in mapping the global distribution of infectious diseases, are seeking to forecast requirements, following the WHO decision last week that the severity of the Ebola outbreak in West Africa makes it ethical to use unregistered drugs and vaccines.

Following that recommendation, the WHO is due to bring together a group of experts to weigh the ethical criteria by which to prioritize who should receive which products. Three classes of drugs – antiviral, antibody-based and vaccines – will be considered at the meeting, which will take place before the end of the month. (See BioWorld Today, Aug. 13, 2014.)

Given that backing from the WHO, "policymakers and funders are now trying to decide which of these options to accelerate into active service. They need good estimates of how many of these drugs and vaccines to manufacture and distribute," Brady said.

Brady and his colleagues have separated the people who need treatment into four categories: those infected with Ebola and people in close association with them such as family members; medical staff treating patients and those handling corpses; support staff such as aid workers and those providing key services and logistical support in dealing with the epidemic; and people who have travelled to the area of the outbreak in West Africa and show possible symptoms of Ebola on their return.

Based on current scientific understanding about probable levels of exposure in these groups, the researchers have calculated the total number of people who might require treatment for a given outbreak and how many will be in each category. The intention is not to provide exact numbers of doses required but rather "to scope potential demand" in different scenarios.

The WHO warned last week that the number of recorded cases "vastly underestimates" the severity of the outbreak. The latest figures show that from Aug. 14 - 16, a total of 113 new cases of Ebola virus disease were confirmed and 84 deaths were reported from Guinea, Liberia, Nigeria and Sierra Leone. That brings the total number of recorded infections to 2,240, with 1,229 deaths.

'BEST BET IS VACCINATION'

Having raised the prospect last Tuesday that an organized, coordinated move to bring experimental therapies to bear on the Ebola infection would be helpful, the WHO appeared to be rowing back in a "situation assessment" it released on Friday, stating, "Recent intense media coverage of experimental medicines and vaccines is creating some unrealistic expectations."

The public needs to understand these products have not been tested in humans and do not have regulatory approval, the WHO said.

"Evidence of their effectiveness is suggestive, but not based on solid scientific data from clinical trials." In addition, most of the experimental drugs are difficult to administer and may require intensive care facilities that are rare in West Africa, the Who noted.

Responding to the forecast by Brady and colleagues, Ian Jones, professor of virology at Reading University, UK, said it was a worthy attempt to put an accurate figure on the need for Ebola treatment, in a process fraught with difficulties. "Treatment requires diagnosis and prophylaxis requires a risk assessment, but neither of these is currently functioning as it should," Jones said.

In addition, animal studies show that early drug or vaccine treatment is key to surviving Ebola infection. "There would be no point in giving current treatments to those at the late stage of disease," Jones said.

In trying to estimate what supplies are needed, it is important to define exactly what any intervention is designed to achieve, said Jonathan Ball, professor of molecular virology at Nottingham University, noting that while treatments have never successfully eradicated viral infections, vaccines have.

"History tells us our best bet is vaccination. But that isn't going to happen tomorrow, and it won't solve the current problem in west Africa," Ball said.

Brady and his colleagues acknowledge that their estimates are crude and have clear limitations. That points to the need for more detailed information on patient contact rates and health care workers' exposure, to increase accuracy.

The analysis as it stands highlights that for drugs to be rolled out evenly and fairly, stocks must be scaled up substantially, Brady said.

"The scale of the ongoing outbreak may tilt the politics and economics to speed the development of a drug or vaccine, but it also makes it difficult to scale up production and distribution," he noted.