Ebola vaccine clears safety test, shows good immune responses

Two independent but coordinated studies, performed at the Walter Reed Army Institute of Research (WRAIR) and the National Institute of Allergy and Infectious Diseases (NIAID), explored the safety and immunogenicity of the investigational vaccine when administered at different dosages.

These pivotal early studies helped inform dose selection for testing of VSV-EBOV vaccine in a large-scale clinical trial in West Africa, noted co-lead author Lt. Col. Jason Regules, adding that they were gratified to see that the vaccine was not associated with significant adverse effects in this very carefully monitored study.

Scientists at the Public Health Agency of Canada's National Microbiology Laboratory originally developed the VSV-EBOV vaccine candidate, one of two Ebola vaccines currently in large scale testing in West Africa. The candidate vaccine does not contain Ebola virus and cannot cause Ebola virus disease.

The trials collectively enrolled 52 volunteers who received either the vaccine candidate or a placebo. Those volunteers given the vaccine received one of two different doses and volunteers were assessed on days 1, 3, 7, 14, and 28 to see if they developed anti-Ebola antibodies.

Twenty-six of 28 volunteers in the vaccine group showed the intended Ebola glycoprotein antibody response within two weeks of vaccination, and all of the volunteers had antibodies within 28 days of receiving the vaccine. Researchers saw a higher antibody response in the vaccine recipients who received the higher vaccine dose.

Researchers saw a robust immune response following a single dose of the vaccine, which could be particularly useful in outbreak interventions, said senior author Col. Stephen Thomas.

Thomas added that they were able to leverage the WRAIR's experience in conducting ethical and safe clinical research experiments to meet a global need.

The study is published in the New England Journal of Medicine.