rVSV-ZEBOV vaccination in people with pre-existing immunity to Ebolavirus: an open-label safety and immunogenicity study in Guinean communities affected by Ebola virus disease (l'essai proches).
Watson CH., Gsell P-S., Hall Y., Camacho A., Riveros X., Enwere G., Vicari A., Nadlaou SD., Toure A., Sani IM., Diallo A., Kolie C., Duraffour S., Ifono K., Maomou A., Dore K., Djidonou HA., Bagayoko A., Damey PP., Camara MN., Diallo FB., Oumar FT., Toure K., Diaby ML., Sylla L., Conde D., Kaba IL., Tipton T., Eggo RM., Marks M., Roberts CH., Strecker T., Günther S., Keita S., Edmunds WJ., Carroll MW., Henao-Restrepo AM.
BackgroundZaire Ebolavirus disease (EVD) outbreaks can be controlled using rVSV-ZEBOV vaccination and other public health measures. People in high-risk areas may have pre-existing antibodies from asymptomatic Ebolavirus exposure that might affect response to rVSV-ZEBOV. Therefore, we assessed the impact pre-existing immunity had on post-vaccination IgG titre, virus neutralisation, and reactogenicity following vaccination.MethodsIn this prospective cohort study, 2115 consenting close contacts ("proches") of EVD survivors were recruited. Proches were vaccinated with rVSV-ZEBOV and followed up for 28 days for safety and immunogenicity. Anti-GP IgG titre at baseline and day 28 was assessed by ELISA. Samples from a representative subset were evaluated using live virus neutralisation.ResultsTen percent were seropositive at baseline. At day 28, IgG in baseline seronegative (GMT 0.106 IU/ml, 95% CI: 0.100 to 0.113) and seropositive (GMT 0.237 IU/ml, 0.210 to 0.267) participants significantly increased from baseline (both p ConclusionsThese data add further evidence of rVSV-ZEBOV safety and immunogenicity, including in people with pre-existing antibodies from suspected natural ZEBOV infection whose state does not blunt rVSV-ZEBOV immune response. Pre-vaccination serological screening is not required.