The Phase 1 trial has been carried out in China. According to a paper published in the medical journal The Lancet, the results show that the vaccine is safe and that it probably has a good efficacy. The drug has been developed by the Beijing Institute of Biotechnology and Tianjin CanSino Biotechnology.
The vaccine candidate is the first to incorporate immunogens from the strain of Ebola that has terrorized West Africa for nearly a year; all other tested Ebola vaccines have been based on the strain that caused an outbreak in Zaire in 1976, according to a research brief.
As part of the Phase 1 trial, scientists administered the new vaccine candidate or a placebo to 120 healthy Chinese adults. Four weeks later, all 40 participants who received a high dose of the vaccine showed a positive immune response, as did 38 out of 40 participants in the low-dose group. Those who had received the high dose produced more antibodies than those in the low-dose group. No serious adverse events were reported. The researchers plan to follow the vaccine recipients to assess long-term immune responses.
Commenting on their research, lead scientists Andrea Marzi from the National Institute of Allergy and Infectious Diseases and Darryl Falzarano from the University of Saskatchewan in Canada wrote in a discussion article to support the research paper: “This adenovirus type-5 Ebola vaccine vector is an example of how quickly existing vaccine platforms can be modified to incorporate a new virus strain, and moved, with minimum testing in animals, into trials in humans during a crisis situation.”
The Lancet study is titled “Safety and immunogenicity of a novel recombinant adenovirus type-5 vector-based Ebola vaccine in healthy adults in China: preliminary report of a randomised, double-blind, placebo-controlled, phase 1 trial.”
Despite the apparent success, many vaccines carry risks. Furthermore, the results so far only relate to a Phase I trial. Ultimately, the effectiveness of Ebola vaccines will only become clear when they proceed to phase 2 efficacy trials in outbreak regions.
