Two-component vector-based vaccine Ad26.ZEBOV, MVA-BN-Filo against Ebola fever: A review of clinical studies

INTRODUCTION. High reactogenicity of the existing Ebola vaccines necessitates the development of safer and more efficacious alternatives. A solution is to use new recombinant vectorbased vaccines, such as Ad26.ZEBOV (a recombinant vaccine based on non-replicating human Ad26 serotype with an inserted glycoprotein gene of Zaire ebolavirus strain) and MVA-BN-Filo (a recombinant vaccine based on modified vaccinia Ankara strain), currently undergoing clinical trials to confirm their efficacy and safety.

AIM. This study aimed to systematize clinical trial data in order to assess efficacy, safety, and immunogenicity of the two-component recombinant Ad26.ZEBOV, MVA-BN-Filo vaccine used to prevent Ebola hemorrhagic fever in various population groups.

DISCUSSION. Literary sources were analyzed in the PubMed, ScienceDirect, and eLIBRARY.RU databases over the period of 2009–2024. Phase I–III clinical trials confirmed that the twocomponent Ebola vaccination regimen (Ad26.ZEBOV, MVA-BN-Filo) provides a strong and sustained immune response. Seroconversion reached 87–95% three weeks after the first administration and up to 100% after revaccination, with immunity lasting for at least a year. Adverse events (local and systemic, mild to moderate severity) were observed in half of the participants; serious adverse events were not associated with vaccination and occurred in less than 1%. In pregnant women, the vaccination did not increase the risk of adverse outcomes while ensuring the transmission of antibodies to the fetuses. In children and adolescents, seroconversion exceeded 90%; revaccination significantly enhanced the immune response. In HIV-infected individuals, seroconversion reached 80–85%, which is comparable to the general population. Malaria or helminthiasis did not reduce the immunization effectiveness. Considering the above, the World Health Organization and the European Medicines Agency approved this vaccination schedule in 2020 in adults and children over one year of age, including those with concomitant infections.

CONCLUSIONS. The two-component Ad26.ZEBOV, MVA-BN-Filo vaccine shows high immunogenicity and a good safety profile. The primary and booster vaccination schedule is effective in adults, children over one year of age, pregnant women, and individuals with concurrent infections, including HIV, malaria, and helminthiasis. The vaccine reduces the risk of Ebola transmission and can be used for a mass immunization strategy in endemic regions and during the disease outbreaks.

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