Two Preclinical Ebola Vaccines Elicit Sustained Immune Responses

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Adverse events occurred more often with the active vaccines than placebo in the week after administration. <i>Photo Credit: National Institute of Allergy and Infectious Diseases (NIAID)</i>
Adverse events occurred more often with the active vaccines than placebo in the week after administration. Photo Credit: National Institute of Allergy and Infectious Diseases (NIAID)

HealthDay News — Two vaccines to prevent Ebola virus disease (EVD) demonstrated immune responses at 1 month that were largely maintained through 12 months, according to a study published in the New England Journal of Medicine.

Stephen B. Kennedy, MD, from the Liberian Ministry of Health, and colleagues initiated a randomized phase 3 trial of the chimpanzee adenovirus 3 vaccine (ChAd3-EBO-Z) and the recombinant vesicular stomatitis virus vaccine (rVSVΔG-ZEBOV-GP) in 1500 adults in Liberia. Safety and immunogenicity were assessed in a phase 2 subtrial. After incidence of EVD declined, the phase 2 subtrial was expanded and the phase 3 component was eliminated.

The researchers found that adverse events occurred significantly more often with the active vaccines than placebo in the week after administration; these included injection-site reactions, headache, muscle pain, feverishness, and fatigue. Within 12 months after injection, serious adverse events were seen in 8%, 9.4%, and 11.8% of the ChAd3-EBO-Z, rVSVΔG-ZEBOV-GP, and placebo groups, respectively. Antibody response developed by 1 month in 70.8%, 83.7%, and 2.8% of those in the ChAd3-EBO-Z, rVSVΔG-ZEBOV-GP, and placebo groups, respectively (both comparisons P <.001). Antibody responses were seen in 63.5%, 79.5%, and 6.8%, respectively, at 12 months (both comparisons P <.001).

"By 1 month after vaccination, the vaccines had elicited immune responses that were largely maintained through 12 months," the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

Reference

Kennedy SB, Bolay F, Kieh M, et al. Phase 2 Placebo-controlled trial of two vaccines to prevent Ebola in Liberia. N Engl J Med 2017; 377:1438-1447

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