Fig. 4: SARS-CoV-2–specific cellular immune responses after Ad26.COV2.S, Ad26.COV2.S.529, or a combination of Ad26.COV2.S and Ad26.COV2.S.529 late booster in adult rhesus macaques.

WA1/2020 (a and b) and Omicron BA.1 (c and d) S-specific T cell responses, as measured in 42 NHP PBMC samples with an IFN-γ ELISpot 6 weeks after the booster/immunization (a and c) and 2 weeks post-challenge with Omicron BA.1. PBMCs were either non-stimulated (i.e., medium stimulated representing background) or stimulated with S WA1/2020 or Omicron BA.1. Background-subtracted counts for individual NHPs are indicated by a dot. The GM response per group is indicated with the red horizontal line. Samples with background-subtracted counts ≤25 were set at 25 for visualization purposes and indicated by open symbols and the dotted line. For all panels, n = 7 animals per group except for the Sham-S.529 group where n = 6 animals and for the Sham-Sham group where n = 8 animals. Comparisons between the sham-immunized group and all other groups with 5-fold Bonferroni adjustment as well as pairwise comparisons between groups except the control sham-immunized group were made with a 2-sided z-test, t-test, or exact Mann-Whitney U-test. ^#p < 0.05; ^##p < 0.01; ^###p < 0.001. Non-significant comparisons are not indicated on the graphs. The complete statistical analysis is reported in Supplementary Table 2. Source data are provided as a Source Data file. ELISpot enzyme-linked immunospot assay, GM geometric mean, IFN-γ interferon gamma, NHP nonhuman primate, PBMC peripheral blood mononuclear cell, S spike, SFU spot-forming units, T timepoint.