| Contributors: |
Huttner, A.; Agnandji, S. T.; Engler, O.; Hooper, J. W.; Kwilas, S.; Ricks, K.; Clements, T. L.; Jonsdottir, H. R.; Nakka, S. S.; Rothenberger, S.; Kremsner, P.; Zust, R.; Medaglini, D.; Ottenhoff, T.; Harandi, A. M.; Siegrist, C. -A.; Krishna, S.; Kremsner, P. G.; Brosnahan, J. S.; Addo, M. M.; Becker, S.; Krahling, V.; Bejon, P.; Njuguna, P.; Kieny, M. -P.; Moorthy, V.; Fast, P.; Savarese, B.; Lapujade, O.; Ahmed, R.; Anderson, J.; Auderset, F.; Borgianni, L.; Brosnahan, J.; Ciabattini, A.; Haks, M. C.; Harandi, A.; Heppner, D. G.; Gerlini, A.; Monath, T.; Ndungu, F.; Ottenhoff, T. H.; Pejoski, D.; Page, M.; Pozzi, G.; Santoro, F.; Dubey, S.; Fernandes, J. F.; Lucchesi, S.; Nakaya, H.; Orourke, F.; van Veen, S.; Vianello, E. |
| Description: |
Objectives: To report 5-year persistence and avidity of antibodies produced by the live-attenuated recombinant vesicular stomatitis virus (rVSV) expressing the Zaire Ebolavirus (ZEBOV) glycoprotein (GP), known as rVSV-ZEBOV (Ervebo®). Methods: Healthy adults vaccinated with 300,000 or 10–50 million plaque-forming units of rVSV-ZEBOV in the WHO-coordinated trials of 2014–2015 were followed for up to 4 (Lambaréné, Gabon) and 5 (Geneva, Switzerland) years. We report seropositivity rates, geometric mean titres (GMTs), and population distribution of ZEBOV-GP ELISA IgG antibodies, neutralizing antibodies (pseudovirus and live-virus neutralization) and antibody avidity; the primary outcome was ZEBOV-GP ELISA IgG GMTs at 4 or 5 years compared with 1 year (Y1) after immunization. Results: Among the 168 eligible vaccinees (Geneva: 97 and Lambaréné: 71) enrolled 1 year post-immunization, 146 (87%) remained enrolled at 4 years (Geneva: n = 88, Lambaréné: n = 58), and 84 (87%, Geneva) at 5 years post-vaccination. ZEBOV-GP ELISA IgG GMTs plateaued, with no declining trend from 1 year through the last time point assessed (1147.8 [95% CI 874.3–1507.0] at Y1 versus 1548.1 [95% CI 1136.6–2108.5] at Y5 in Geneva volunteers receiving ≥10 million plaque-forming units of rVSV-ZEBOV), their avidity matching that of ZEBOV convalescents. Live-virus neutralizing antibodies were detected for shorter periods and in fewer vaccinees (53/95 [56%] at Y1 versus 35/84 [42%] at Y5 in Geneva volunteers, all dose levels). Discussion: Titres at Y1 emerged as a correlate of antibody persistence at Y5. The findings of persistent ZEBOV-GP ELISA IgG titres yet shorter-lasting, lower titres of live-virus neutralizing antibodies suggest the contribution of antibody-mediated protective mechanisms other than neutralization. Long-term clinical efficacy of rVSV-ZEBOV, however, requires further study. |