Initial results of the Ebola vaccine trials in Africa and Europe
Ebola virus
The initial results of a clinical Phase I trial of a potential vaccine against the dreaded Ebola virus are now available. At the Hamburg-Eppendorf University Medical Center (UKE), in Geneva (Switzerland), Lambaréné (Gabon) and in Kilifi (Kenia) scientists were testing the „rVSV-ZEBOV“ vaccine on a total of 158 healthy adult volunteers. The initial results were published today by the New England Journal of Medicine (NEJM).
"The preliminary results for tolerability, safety, and the immune response to the vaccine candidate are promising," explains Prof Marylyn Addo. The specialist for infectious diseases is a DZIF Professor at the UKE at Hamburg; she authored the recent publication outlining the results for all four sites. The scientists involved are participants in VEBCON, a consortium of experts founded by the WHO, the goal of which is rapid and coordinated clinical testing of the Ebola vaccine in Africa. A vaccine is still urgently needed, since the current Ebola epidemic has not yet been defeated and future outbreaks cannot be ruled out.
About the trial
A total of 158 healthy volunteers at the four locations were vaccinated with increasing doses of the potential vaccine. A double-blind study was conducted in Geneva. The rVSV-ZEBOV vaccine used is an attenuated, genetically modified strain of vesicular stomatitis virus (VSV), wich bears a surface protein of the Ebola virus. The goal is to help the vaccinated person's immune system produce antibodies to prevent an outbreak of the disease upon contact with the Ebola virus. For the first time, scientists have tested the vaccine's safety and tolerability in people, as well as the human immune response to it.
Important results
Safety and tolerability: No serious adverse reactions associated with the vaccine have been observed. Since it is a live vaccine, small amounts of the vaccine virus were found in the blood, as expected, but only in the first few days. Virus replication appears to be controlled and limited by the immune system. No viruses were detected in saliva and urine.
Effect on the immune system: The vaccine stimulated the immune systems of all participants to produce antibodies specifically targeting the Ebola surface protein. The antibodies produced were able to inhibit the virus in vitro. "The results demonstrate, that the new vaccine may be used successfully in dramatic epidemic situations", says Prof Stephan Becker, who analysed the immune response of the volunteers in his lab at the Philipps-Universität Marburg.
"The adverse reactions were generally mild or moderate and within the limits of what can be expected when using live vaccines", explains DZIF Professor Peter Kremsner from the University Hospital Tuebingen; Kremsner headed the trial in Gabon.
The initial results of the trials will now be utilized in further trials that will use the optimal doses previously determined. In Guinea, where the Ebola epidemic still claims many lives, the vaccine is already being tested in a larger Phase II/III trial based on the initial results of the vaccine trial described here, and people in contact with Ebola patients are being vaccinated. About 10,000 people are expected to participate in these trials in the coming weeks.
The German Center for Infection Research (DZIF) supported the preparation of the trial at the UKE in Hamburg. DZIF, the Federal Ministry of Health (BMG), and the British Wellcome Trust provided the funding to prepare and implement the clinical trial. The Canadian Health Authority donated the vaccine candidate to the WHO, which then made it available for these trials. All parties involved are thus responding quickly and jointly to the dramatic Ebola epidemic in West Africa. In preparing the trial, the DZIF scientists in Hamburg, Gießen-Marburg-Langen, and Tübingen worked closely with the Paul-Ehrlich-Institut (PEI), which, as a partner of the DZIF, supports research into new vaccine platforms. In Hamburg the trial was conducted in collaboration with the Heinrich Pette Institute and the Bernhard Nocht Institute.
