Protective efficacy against SARS-CoV-2 inoculation after vaccination of aged rhesus macaques. (A–D) Animals were challenged with 10⁵ TCID₅₀ SARS-CoV-2 administered intranasally and intratracheally 13 wk after the first vaccine dose. Data from a challenge of naive animals (n = 4) using an identical challenge strain, challenge regimen, and readouts were added to the sham control group data, collectively referred to as pooled control, to increase statistical power. (A) Cumulative viral load (sgmRNA) in daily nasal (left panel) and tracheal (right panel) swabs, defined by AUC calculation and expressed as log₁₀ AUC (sgmRNA copies/ml × days) from 19 NHPs. Note that for AUC calculation, the day of death of all animals was aligned to day 7 to allow combining data from animals euthanized at day 7 and day 8. (B) Cumulative viral load (sgmRNA) in BAL, obtained every other day during the follow-up period, defined by AUC calculation and expressed as log₁₀ AUC (sgmRNA copies/ml × days) from 13 NHPs. Note that it was only possible to perform BAL on a limited number of animals, and it was decided to exclude the one-dose 10¹¹-vp Ad26.COV2.S group. (C) Viral load (sgmRNA) in lung tissue. Viral load was measured in each individual lung lobe (seven) of each animal (19 NHPs) and expressed as log₁₀ sgmRNA copies/gram. A lower right lung lobe sample of one animal in the pooled control group was not available. (D) Fever duration, defined as AUC of the net temperature increase for each animal (19 NHPs) during the first 6 consecutive d of the follow-up period relative to a prechallenge baseline period. Red horizontal lines represent group geometric means; the dashed horizontal line indicates the LLOQ. Open symbols denote samples at LLOQ. Mean nasal and trachea swabs and BAL AUC values of each group were pairwise compared using Tobit ANOVA with post hoc z-test. Mean net temperature difference AUCs were pairwise compared between groups by t test.