West Africa Ebola Outbreak 2013-2014: Disease, Treatments, and Global Impact

Jill E. Weatherhead, MD; Laila Woc-Colburn, MD


February 03, 2015

In This Article

Vaccine Development

Vaccine development for Ebola virus was under way before the onset of the most recent epidemic; however, no vaccine is currently available or approved for use. The two leading candidates targeting virus glycoproteins are recombinant chimpanzee adenovirus serotype 3 (cAd3) and a recombinant vesicular stomatitis virus (rVSV-EBO).[1,11] Both vaccines have shown efficacy for preexposure prophylaxis with 100% protection in nonhuman primates at 4-5 weeks after a single dose.[1,11]

The cAd3 vaccine candidate, which is currently in a phase 1 clinical trial, has been evaluated as a preexposure prophylaxis candidate. Study results in nonhuman primate trials have demonstrated 100% protection from Ebola virus at 5 weeks and 50% protection at 10 months.[1] When boosted, the vaccine showed 100% protection at 5 weeks and at 10 months.[1]

The rVSV vaccine candidate has provided complete protection to animal models (including nonhuman primates) when administered intramuscularly, intranasally, or orally after exposure to a lethal challenge dose of Ebola virus.[3] As a result, rVSV vaccine may be a candidate for postexposure therapy.[3]

For both vaccine candidates, phase 1 clinical trials have shown that the strong humoral and cell-mediated immunogenic response generated were dose-dependent.[11] These higher doses for improved immune response were associated with minor adverse effects in 70% of subjects.[11] It is also unclear how these vaccines will respond in areas endemic with such infections as malaria, which are known to produce reduced immunogenicity to vaccines in coinfected patients.[11]

Summing It Up

The current Ebola epidemic continues to devastate West Africa. Although many therapeutic options are under development, no medication is currently available for prophylaxis or treatment of EVD. Furthermore, despite promising results in nonhuman primate models, vaccines for pre- and post-prophylaxis are also not currently available.

The local and global impact of the current Ebola epidemic is significant. Greater worldwide interconnectedness has made this epidemic of huge importance not only for the people living in West Africa, but for all people around the globe.


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