The stability profile of a vaccine has important implications for storage, cold chain management and field deployment. The heterologous prime-boost Janssen Ebola vaccine regimen demonstrated an acceptable safety profile and durability of Ebola-specific immune responses in Phase I studies in healthy adults.
Potency (infectious titre) of both components of the Ad26.ZEBOV/MVA-BN-Filo regimen were assessed using qPCR-based potency assay and flow cytometry during real-time and accelerated stability studies, conducted between −80 °C and 25 °C. Additionally, vaccine potency was assessed following agitation, temperature cycling, freeze-thawing and while in the injection system.
Ad26.ZEBOV remained stable for 24 months when frozen and at 2–8 °C; MVA-BN-Filo remained stable for 24 months frozen and 12 months at 2–8 °C. Potency of both vaccines was maintained during temperature cycling, agitation and freeze-thawing. When exposed to high temperatures (up to 40 °C) in a syringe/needle both vaccines remained stable for at least 6 h. The vaccines are expected to maintain potency for 36 months when frozen (based on extrapolation of observed stability).
The findings of this study indicate that the stability of the Ad26.ZEBOV/MVA-BN-Filo is likely suitable for field deployment in regions at risk of Ebola outbreaks, where cold chain maintenance is challenging owing to infrastructure and resource limitations.