Ebola Vaccine Study in West Africa, April 3, 2017: Study volunteer receives inoculation at Redemption Hospital in Monrovia on the opening day in Liberia of PREVAC, a Phase 2 EbolaCredit: NIAID
Two newly published clinical studies, at three clinics in Sierra Leone’s Kambia District, have shown the Ad26.ZEBOV and MVA-BN-Filo Ebola vaccine regimens are safe, well tolerated and produce strong immune responses in children and adults.
The authors, led by Muhammed Afolabi, an assistant Professor at the London School of Hygiene and Tropical Medicine (LSHTM), enrolled and randomly assigned 576 healthy children and adolescents (aged 1 - 17 years). In one publication, they evaluated the safety and immunogenicity of the vaccine regimen, specifically the ability to initiate the production of Ebola virus glycoprotein-specific binding antibodies in adequate concentration.
Twenty one days after administration of the second dose, antibody responses were observed in 98% of children aged 12–17 years, 99% of children aged 4–11 years, and 98% of participants aged 1–3 years. They concluded that the vaccine regimen was well tolerated with no safety concerns in children aged 1–17 years, and induced robust humoral immune responses, suggesting the suitability of this regimen for Ebola virus disease prophylaxis in children.
"We were able to record higher immune responses in the younger age group compared to the older groups. If Ebola rears its ugly head again, we have a potent vaccine not only for adults, but also for children up to 17 years old,” Afolabi told Nature Africa.
In the clinical trial that focused on adults using the same Ad26.ZEBOV and MVA-BN-Filo regimen, Daniela Manno, of the London School of Hygiene and Tropical Medicine, and colleagues, recruited 443 participants, and found that both regimens were well tolerated with no safety concerns. The vaccine-induced humoral immune responses, was reported in 98% of participants that received the regimen.
The authors concluded that the vaccine’s tolerance and immunogenicity, with persistent humoral immune responses, support its use for Ebola virus disease prophylaxis in adults. "We also showed that an additional dose of vaccine, produced a rapid and a strong increase in antibody concentration, supporting the recommendation of a booster dose in previously vaccinated people when there is an imminent risk of Ebola infection," Manno told Nature Africa.
Matshidiso Moeti, WHO Regional Director for Africa, described the findings as extremely good news. For John Nkengasong, Director of the Africa Centres for Disease Control and Prevention (Africa CDC), the studies have a huge implication for Ebola control efforts in Africa. “Those were encouraging results. It means we have actually expanded our toolkits to fight an eventual Ebola outbreak.” he says.
