Fig. 3. Effects of age-dependent vaccine efficacy on the impacts of prioritization strategies.

(A) Diagram of hypothetical age-dependent vaccine efficacy shows decrease from 90% baseline efficacy to 50% efficacy among individuals aged 80+ years, beginning at age 60 (dashed line). (B and C) Percent reduction in deaths in comparison with an unmitigated outbreak for transmission-blocking all-or-nothing vaccines with either constant 90% efficacy for all age groups (solid lines) or age-dependent efficacy shown in (A) (dashed lines), covering scenario 1 [0.2% rollout per day, R₀ = 1.15; (B)] and scenario 2 [0.2% rollout per day, R₀ = 1.5 (C)]. Black dots indicate break points at which prioritized demographic groups have been 70% vaccinated, after which vaccines are distributed without prioritization. Shown are contact patterns and demographics of the United States (38, 53); all-or-nothing and transmission-blocking vaccine.