by Research on developing an effective Ebola vaccine gained momentum after the 2014-2016 outbreak in West Africa that caused over 11,000 deaths. Several vaccine candidates entered clinical trials to evaluate their safety and ability to trigger an immune response. The two leading vaccine candidates that have shown most promise are the rVSV-ZEBOV vaccine and the Ad26-ZEBOV-GP/MVA-BN-Filo vaccine.
The rVSV-ZEBOV vaccine was the first to be tested on humans. It uses a genetically engineered vesicular stomatitis virus (VSV) that possesses the Ebola virus’s glycoprotein on its surface. Phase 1 and 2 clinical trials starting in 2015 found it to be well-tolerated and highly effective in triggering antibodies against Ebola virus. Ebola Vaccine It received regulatory approval in several countries based on these results.
The Ad26-ZEBOV-GP/MVA-BN-Filo vaccine employs a two-dose regimen – it uses an adenovirus serotype 26 vector for the first dose followed by a Modified vaccinia Ankara vector for the second dose. Both doses contain the Ebola virus’s glycoprotein. Phase 1 trials again showed good safety and strong immune responses. Phase 3 trials involving thousands of individuals were initiated during the 2014-2016 outbreak to assess real-world effectiveness. Preliminary analyses found the vaccine to be nearly 100% effective in preventing Ebola.
Licensure and Recommendations
Based on the promising results from various efficacy and effectiveness trials, the rVSV-ZEBOV vaccine received regulatory approval from the European Medicines Agency in July 2019 under the name Ervebo. It gained a similar recommendation for use in emergency situations from the World Health Organization (WHO).
In October 2019, the Ad26-ZEBOV/MVA-BN-Filo vaccine was also recommended by the WHO for use in people at risk of Ebola outbreaks. Manufactured by Johnson & Johnson under the name Jynneos, it offers the advantage of a two-dose schedule over a single month as opposed to Ervebo which requires careful temperature control during transport and storage.
Both vaccines have shown sufficient safety and efficacy to be deployed during Ebola outbreaks to protect at-risk populations and health workers. Their availability now provides a much-needed tool against this deadly virus.
Challenges in Mass Vaccination
Logistical challenges remain in conducting large-scale vaccination programs during Ebola outbreaks in remote African regions with limited infrastructure and healthcare facilities. Vaccine hesitancy also poses a threat if misinformation spreads about side effects or perceived dangers.
During the 2018-2020 Ebola outbreak in the Democratic Republic of Congo, over 300,000 people received the rVSV-ZEBOV vaccine as part of “ring vaccination” efforts by WHO and local health authorities. While this helped bring the outbreak under control, difficulties arose in areas with ongoing conflict where reach and community acceptance were lower. The logistics of maintaining cold storage and transport further complicated deployment to isolated villages.
New research aims to develop thermostable Ebola vaccines that do not require refrigeration, which could vastly improve access in remote or insecure regions. Dry-powder and solid-dose formats are some options being explored. Vaccine strategies focusing first on contacts of known cases and villages at high risk may also optimize utilization of limited vaccine supplies during emergencies. Continued community education efforts will additionally be paramount to overcoming fear and skepticism.
Long-Term Prevention through Vaccination
Widespread vaccination offers the best hope for breaking the cycle of Ebola outbreaks over the long run. Researchers are evaluating strategies for regular immunization of high-risk populations in Africa to establish protective herd immunity. Surveillance and rapid response systems would still need to screen for cases, but the risk of large epidemics could be drastically reduced.
Clinical research is also advancing new vaccine platforms. A universal filovirus vaccine offering protection against Ebola as well as the Marburg virus is in clinical trials. DNA vaccines, recombinant protein vaccines, and vaccine combinations are other approaches in early or preclinical testing. As the science progresses, the goal is to develop broadly immunogenic vaccines that are affordable to manufacture, stable at higher temperatures, and provide durable immunity with few doses.
With continued global cooperation and support for research, the successful development of next-generation Ebola vaccines could bring the world closer to gaining control over this deadly disease. Widespread immunization holds immense promise to shield at-risk populations in Africa and curb Ebola’s capacity to trigger large recurrent outbreaks that threaten global health security.
*Note:
1.Source: Coherent Market Insights, Public sources, Desk research
2.We have leveraged AI tools to mine information and compile it
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