Fig. 3: COH04S1 vaccine immunogenicity in NHP.

a Study design. African green monkey NHP were vaccinated with COH04S1 vaccine using two-dose (COH04S1-2D; n = 6) or single-dose (COH04S1-1D; n = 6) vaccination regimens as indicated. Mock-vaccinated NHP (n = 3) and NHP vaccinated with empty sMVA vector using the same dose vaccination regimens (n = 3) were included as controls. Six weeks after immunization, NHP were IN/IT challenged with SARS-CoV-2 USA-WA1/2020 reference strain. Bronchoalveolar lavages (BAL) and oral and nasal swab samples for viral load analysis were collected at multiple time points post-challenge. A subset of animals in each group were necropsied at day 7 and 21 post-challenge for viral load and histopathology analysis. b–d Binding antibody titers. S, RBD, and N antigen-specific binding antibody titers were measured at the indicated time points in serum samples of COH04S1-2D and COH04S1-1D-vaccinated NHP via ELISA. Data is presented as geometric mean values ± geometric s.d. Two-way ANOVA followed by Sidak’s multiple comparison test was used. e VOC-specific antibody titers. S-specific binding antibody titers were measured at day 62 by ELISA using S antigens based on the Wuhan-Hu-1 reference strain or several SARS-CoV-2 VOC, including Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2). Endpoint titers are presented as geometric mean values ± geometric s.d. Two-way ANOVA with Sidak’s multiple comparison test was used for statistical analysis. f BAL antibody titers. S, RBD, and N antigen-specific binding antibody titers were measured by ELISA at day 42 in BAL samples of COH04S1-IM and COH04S1-IN vaccine group. Endpoint titers are presented as geometric mean values ± geometric s.d. Two-way ANOVA with Sidak’s multiple comparison test was used. g NAb titers. NAb titers were measured by PRNT assay against SARS-CoV-2 infectious virus in serum samples of COH04S1-vaccinated NHP. Serum dilutions reducing the plaque number by 50% (ID50) are presented as geometric mean values ± geometric s.d. Two-way ANOVA followed by Sidak’s multiple comparison test was used to compare ID50 values. PRNT-assayed NAb titers measured in serum samples of healthcare workers (N = 14) vaccinated two times with Pfizer-BioNTech BNT162b2 mRNA vaccine were included. Dotted lines in b–g indicate the lower limit of detection. Green and purple triangles indicate the time of vaccination. Red triangles indicate time of pre-challenge sampling. h–i T cell responses. IFNγ-, IL-2-, and IL-4-expressing S- and N-antigen-specific T cell responses were measured at day 42 by ELISPOT. Bars represent mean values, lines represent ± s.d. Two-way ANOVA followed by Tukey’s multiple comparison test was used. Dotted lines indicate the arbitrary positive threshold of 30 spots/106 cells. *0.05 < p < 0.01, **0.01 < p < 0.001, ***0.001 < p < 0.0001, ****p < 0.0001.