A year on from the first confirmed case of Ebola, nearly 25,000 people have been infected with the disease. Although the epidemic appears to be slowing down and trials into potential treatments have begun, there are many lessons still to be learnt about our ability to prepare for and respond to epidemics.
Dr Jeremy Farrar, Wellcome Trust Director, and Seth Berkley, CEO of Gavi, look back over the events of the past year.
A year ago, scientists confirmed that the cause of a deadly fever in Guinea, which had already killed 59 people and was continuing to spread, was the Ebola virus. Twelve months later, trials for a second promising vaccine have begun in Guinea, with a first trial already underway in Liberia. But this progress doesn't mean that the Ebola crisis has been solved or that we're better prepared for future epidemics yet.
The best news is that the epidemic is coming under control. In the week to March 8, 116 new cases were reported from Sierra Leone and Guinea, compared to a thousand or more per week at the height of the outbreak. Liberia reported no new confirmed cases for the second consecutive week. This reduction is mainly thanks to the implementation of basic hygiene and public-health procedures: the rehydration of patients; the separation of the healthy from the sick, the dying and the dead; the use of diluted bleach for washing; and a better understanding of cultural practices so that families and communities can be protected from the risk of, for example, preparing dead bodies for funerals when they are still highly infectious.
Yet applying higher-tech solutions, such as a vaccine, has been much slower going. Several Ebola vaccines were first conceived more than a decade ago but then shelved. Much more could and should have been done in advance of this outbreak, measures that would have enabled trials to begin as soon as the alarm was raised. Critical safety and dosing studies could have been carried out years ago rather than waiting until an outbreak occurred.
The medical-research, pharmaceutical and global-health communities have hardly dragged their heels as the past year's epidemic progressed, nor did affected governments, donor governments and private philanthropists. But efforts to develop a vaccine were dogged by a lack of consensus on whether clinical trials were necessary or appropriate in an epidemic context. And when agreement was finally reached, trials took too long to get started. A lack of agreement over trial protocols caused further delays.
As a result, no trial was ready to go until the beginning of 2015, and some still have not started. Procedural hurdles are there for good reasons, primarily safety. But delays in this case have likely cost lives and certainly jeopardized trials, which require large numbers of participants. Ebola cases are thankfully now in decline, but one study – of the drug brincidofovir – has already collapsed as a result.
The problem with diseases like Ebola, which kill ferociously but occur only sporadically, is that there is simply no market for related medical interventions. There are usually only a few hundred cases every few years, and typically in poor African countries. Companies would unlikely see any return on the substantial investment required to get a drug or vaccine through trials. The current trials are happening only because manufacturers, philanthropists and donor governments agreed to share the costs. Who will pay for the administration of each dose, if they are approved, remains unclear.
Until we can develop some way to fund research and development related to likely future epidemics and test new drugs and vaccines swiftly during epidemics, we will remain vulnerable to outbreaks. We need to stop waiting until we see evidence of an infectious disease becoming a global threat before we treat it like one.
The medical and scientific community needs to continue identifying other potential disease threats, and develop the necessary tools to estimate how big a risk they pose. There are probably more than a dozen known diseases, including other haemorrhagic fevers like Marburg and Lassa fever, or henipavirus, for which markets are unlikely to ever exist but which could cause Ebola-style crises in the future. There is already modelling to identify the most significant threats: Risk factors include diseases caused by RNA viruses, and diseases that are endemic in animal populations, especially when these have close contact with humans.
We also need further research into the biology of such diseases. Understanding their genetic sequences, their animal hosts and their mode of transmission – from animals to humans and then from human to human – can make it easier to spot and counter epidemic threats sooner. Areas of focus must include these diseases' interactions with the immune system, and identifying biological signatures that indicate greater transmissibility or virulence.
Public health authorities need to consider now how best to test drugs and vaccines safely and quickly once the next outbreak occurs. Not only do delays deprive patients of potentially life-saving treatments, they also deny scientists the chance to observe the efficacy of treatments at the height of an epidemic.
Finally, we need to invest in better surveillance to spot patterns in future outbreaks sooner. This Ebola outbreak has differed from previous occurrences not because the pathogen itself has changed but because of the environment in which it emerged. For the first time, Ebola spread in more populated and urban areas, which enabled it to infect and kill more people faster than ever before. Preventing similar outbreaks in the future means identifying such new factors earlier and reacting more quickly.
One year on, this outbreak may now appear to be subsiding. But there will be other epidemics, including Ebola itself. We can't afford not to learn the lessons of this one.