Characterization of the immune response induced by the homologous and heterologous booster vaccination schedules against Ebola Virus to inform re-vaccination strategies

Ebola virus (EBOV) disease remains a serious and fatal disease in humans despite the advances made in the last years with respect to preventive vaccines and therapeutics. EBOV remains a major public health problem in several regions of Africa, particularly in in the Democratic Republic of Congo (DRC)which registers the highest frequency of outbreaks; and constitutes a global threat. Two prophylactic Ebola virus vaccines are available and licensed in many countries, namely the single-dose rVSV-ZEBOV and the two-dose Ad26.ZEBOV (Zabdeno)/ MVA-BN-Filo (Mvabea) vaccine schedule.

However, there are issues. The higher number of vaccinated individuals in DRC. Also, there are cases of documented breakthrough Ebola infection. Therefore, there is a need for booster vaccination. However, different schedules and vaccine combinations are possible. Therefore, our goal is to characterize and assess differences in vaccine-induced EBOV-specific immune responses after homologous to heterologous booster vaccine schedules. To enumerate and phenotype the differences in EBOV-specific binding antibodies, neutralizing antibodies, and the functional T and B cell recall responses, and to compare them between booster vaccine schedules. We will also study the impact of potential influential factors such as Malaria on the vaccine-induced immune response to inform re-vaccination guidelines.