Fig. 4: Vaccine efficacy by D29 ID₅₀ titre for each ENSEMBLE geographic region and for United States participants in ENSEMBLE compared to two other efficacy trials.

a–c, Vaccine efficacy (solid lines) in baseline SARS-CoV-2 seronegative per-protocol vaccine recipients by D29 PsV-nAb ID₅₀ titre to D614G in ENSEMBLE by geographic region (US, United States; Lat Am, Latin America; S Afr, South Africa) (a); D29 predicted geometric mean PsV-nAb ID₅₀ titre to strains that circulated during follow-up in each designated geographic region (see Supplementary Note 2) (b); and D57 ID₅₀ titre to D614G in COVE, D29 ID₅₀ titre to D614G in ENSEMBLE (US), D56 ID₅₀ titre to D614G in COV002, all estimated using the Cox proportional hazards implementation of ref. ⁴⁴ (c). The dotted lines indicate bootstrap pointwise 95% CIs. The follow-up periods for the VE assessment were: a, ENSEMBLE-US, 1–53 d post D29; ENSEMBLE-Lat Am, 1–48 d post D29; ENSEMBLE-S Afr, 1–40 d post D29; b, COVE (doses D1, D29), 7–10 d post D57; ENSEMBLE-US, 1–53 d post D29; COV002 (doses D0, D28; VE defined as 1 − relative risk of whether or not an event occurred =28 d post D28 until the end of the study period). The histograms are an estimate of the density of D29 ID₅₀ titre in ENSEMBLE (including by geographic region in a and b). The blue histograms are estimates of the densities of ID₅₀ titres in baseline SARS-CoV-2 negative per-protocol vaccine recipients in COVE. Curves are plotted over the range from 10 IU₅₀ ml⁻¹ to the 97.5th percentile of the marker for COVE and from the 2.5th percentile to the 97.5th percentile for ENSEMBLE. Baseline covariates adjusted for were: ENSEMBLE: baseline risk score and geographic region; COVE: baseline risk score, comorbidity status and community of colour status; COV002: baseline risk score.

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