One year ago West Africa was descending into chaos. As the Ebola death toll approached 1,000 for the first time ever and Liberia closed its borders, the World Health Organization declared the situation an international health emergency. Experimental drugs were cautiously put to use to try to treat those infected, but what was urgently needed to stop the spread was a vaccine. Now, 12 months on, it looks very much like we have one.
Interim results published Friday in the medical journal the Lancet provide clear evidence that the rVSV-ZEBOV candidate vaccine currently undergoing phase 3 trials – the final phase before vaccines can be licensed – is not only safe in the short-term, but also highly effective at protecting people from the Ebola virus circulating in Guinea.
What’s more, the results imply that the vaccine also helps reduce cases of Ebola in the broader community, beyond those vaccinated, suggesting that we may now have an extremely effective way of ending the ongoing outbreak.
That must now be the priority. While more research may be needed to establish the long-term protection and safety, use of this vaccine needs to be immediately extended beyond the trials in Guinea and made available to ring vaccinate people in Sierra Leone and wherever else outbreaks occur. Similarly health care workers in affected regions should be offered access to this vaccine now, as they are often the first exposed to any new cases.
More than 11,000 people have lost their lives to this disease, with nearly 28,000 infected since the beginning of the epidemic. And even though it appears to have peaked, with the number of new cases dropping to just a couple of dozen a week and just six cases in Liberia since May, the risk of resurgence remains present. People are still losing their lives and health care workers are still being infected – two in Guinea in the last week alone. We must vanquish this outbreak; zero cases is the only acceptable outcome. While the infection is still present, it is hard to practice medicine and live a normal life when any minor illness can be seen as an early stage of an Ebola infection. We should not underestimate the ease with which this could come back; we should be anticipating that possibility and be ready to act should we need to.
The evidence now suggests that this vaccine provides a means of doing so. Despite the initial delays, W.H.O., manufacturers, researchers and civil society organizations, working with governments, responded rapidly in the face of this devastating health crisis, fast-tracking candidate vaccines through clinical trials at record speed, and for this they should be applauded. Not only have they established that rVSV-ZEBOV is safe and highly effective, producing a result of huge public health significance, but they were bold enough to move forward with an unconventional and quite unique study design. This has helped establish an effective strategy that can potentially end the epidemic and help prevent future outbreaks from spiraling out of control.
This strategy, called ring vaccination, involved vaccinating everyone an infected person had come into contact with, thereby creating a protective ring that helps stop the virus from spreading further. This technique is not new and ultimately played a role in the eradication of smallpox. However in the Ebola trial, which involved vaccinating around 3,500 subjects in 90 “rings”, this approach proved so successful that the Independent Data Safety and Monitoring Board made the decision to abandon the delayed vaccination of a second control group.
In addition to this, a reduction in the number of cases of infection occurring outside these rings was observed, implying that a certain level of herd immunity was achieved, although more research will be needed to establish that. But even so the fact that the vaccine appeared to protect every single subject bodes well, and the hope now is that this will now enable us to protect entire communities effectively without the need for mass vaccinations.
But to do that and to end this epidemic we need to be able to apply this strategy wherever it is needed, not just where the trials are currently being held. It is also important that the trials continue so we can learn more about this vaccine, to fully understand its duration of protection and to establish long-term safety and effectiveness, which will be critical for regulators to provide a permanent license. We will also need further trials to develop improved vaccines that are more temperature stable, have a long shelf life and protect against multiple strains to create stockpiles of vaccines to assure Ebola never spins out of control again.
But we must not lose sight of the fact that this is not just a research exercise; it is a public health intervention. This vaccine has already sat on a shelf for a decade; if we were still seeing 1,000 new cases a week we would not think twice about making it available immediately.
Ultimately this trial is a huge success and great cause for celebration. Indeed we couldn’t have hoped for more positive results, we now have a duty to fully act on them.
Dr. Seth Berkley, a medical doctor and epidemiologist, is chief executive of the Gavi, The Vaccine Alliance, an international organization that works to improve access to new and underused vaccines in low-income countries.