Fig. 4. Effects of existing seropositivity on the impacts of prioritization strategies.

(A to C) Percent reductions in (A) infections, (B) deaths, and (C) years of life lost (YLL) for prioritization strategies when existing age-stratified seroprevalence is incorporated [August 2020 estimates for New York City; mean seroprevalence 26.9% (28)]. Plots show reductions for scenario 2 (0.2% rollout per day, R₀ = 1.5) when vaccines are given to all individuals (solid lines) or to only seronegatives (dashed lines), inclusive of 96% serotest sensitivity, 99% specificity (54), and approximately 3 months of seroreversion (supplementary materials, materials and methods) (29). Shown are U.S. contact patterns and demographics (38, 53), all-or-nothing and transmission-blocking vaccine with 90% vaccine efficacy. Lower and higher seroprevalence examples are provided in figs. S12 and S13, respectively.