Safety and Immunogenicity of Novel Adenovirus Type 26– and Modified Vaccinia Ankara–Vectored Ebola Vaccines

Among 87 study participants (median age, 38.5 years; 66.7% female), 72 were randomized into 4 groups of 18, and 15 were included in the open-label group. Four participants did not receive a booster dose; 67 of 75 study vaccine recipients were followed up at 8 months. No vaccine-related serious adverse events occurred. No participant became febrile after MVA-BN-Filo, compared with 3 of 60 participants (5%; 95% CI, 1%-14%) receiving Ad26.ZEBOV in the randomized groups. In the open-label group, 4 of 15 Ad26.ZEBOV recipients (27%; 95% CI, 8%-55%) experienced fever. In the randomized groups, 28 of 29 Ad26.ZEBOV recipients (97%; 95% CI, 82%- 99.9%) and 7 of 30 MVA-BN-Filo recipients (23%; 95% CI, 10%-42%) had detectable Ebola glycoprotein-specific IgG 28 days after primary immunization. All vaccine recipients had specific IgG detectable 21 days postboost and at 8-month follow-up. Within randomized groups, at 7 days postboost, at least 86% of vaccine recipients showed Ebola-specific T-cell responses.