In a study published in the journal The Lancet, researchers presented the results of a phase 1 trial for an Ebola vaccine. Developed by Tianjin CanSino Biotechnology and the Beijing Institute of Biotechnology, the vaccine is the first to be based off the virus strain responsible for the 2014 outbreak in West Africa.
Led by Feng-Cai Zhu, researchers tested for immunogenicity and safety in the vaccine developed with the 2014 Zaire Guinea strain. Before this, Ebola vaccines were designed using the 1976 Zaire strain as basis. For the trial, 120 health adults participated, each one randomly assigned to receive a low dose of the vaccine, a high dose of the vaccine or a placebo.
After 28 days of receiving the vaccine, 38 participants from the low-dose group and everyone in the high-dose group developed positive immune responses, with more antibodies being produced the higher the administered dose was. Those in the placebo group did not show specific immune responses.
The trial was not able to determine, however, if the immune response experienced by participants will ultimately offer protection against the Ebola virus. Only further tests in West Africa will be able to show true effectiveness but it is still notable that even at high doses the vaccine did not produce adverse effects.
"These results only assess immune response up to 28 days, so we plan to assess the persistence of the specific immune response by following up the vaccine recipients of this study," said Zhu.
Another concern warranting further study is the vaccine's tendency to increase HIV risk.
According to Darryl Falzarano from Canada's University of Saskatchewan and Andrea Marzi, from the National Institutes of Health's National Institute of Allergy and Infectious Diseases, the adenovirus type-5 vector used in the Ebola vaccine shows how easy it is to modify existing platforms to accommodate new virus strains, highlighting minimum testing in animals that can quickly move to human trials in the event of a crisis. They, however, pointed out that how effective the vaccine will be can only be ultimately determined when phase 2 trials begin in West Africa.
The study received funding support from the China National Science and Technology, Tianjin CanSino Biotechnology and the Beijing Institute of Biotechnology. The phase 1 trial was carried out from Dec. 28, 2014 to Jan. 9, 2015 in Taizhou County in China's Jiangsu Province, followed by a 28-day follow-up period.
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