Novel safe, immunogenic, and effective vaccines are needed to control the COVID-19 pandemic, caused by SARS-CoV-2. Here, we describe the safety, robust immunogenicity, and potent efficacy elicited in rhesus macaques by a modified vaccinia virus Ankara (MVA) vector expressing a full-length SARS-CoV-2 spike (S) protein (MVA-S). MVA-S vaccination was well tolerated and induced S and receptor-binding domain (RBD)-binding IgG antibodies and neutralizing antibodies against SARS-CoV-2 and several variants of concern. S-specific IFNγ, but not IL-4, -producing cells were also elicited. After SARS-CoV-2 challenge, vaccinated animals showed a significant strong reduction of virus loads in bronchoalveolar lavages (BAL) and decreased levels in throat and nasal mucosa. Remarkably, MVA-S also protected macaques from fever and infection-induced cytokine storm. Computed tomography and histological examination of the lungs showed reduced lung pathology in MVA-S-vaccinated animals. These findings favor the use of MVA-S as a potential vaccine for SARS-CoV-2 in clinical trials.
Keywords: COVID-19; MVA vaccine; SARS-CoV-2; efficacy; immunogenicity; rhesus macaques; safety; spike.
Copyright © 2022 Mooij, García-Arriaza, Pérez, Lázaro-Frías, Verstrepen, Böszörményi, Mortier, Fagrouch, Kiemenyi-Kayere, Niphuis, Acar, Meijer, Stammes, Kondova, Verschoor, GeurtsvanKessel, de Bruin, Sikkema, Luczkowiak, Delgado, Montenegro, Puentes, Rodríguez, Bogers, Koopman and Esteban.