Impact of vaccination in an HIC setting with substantial prior transmission and high vaccine access (Category 1).

We assume mRNA-1273 is implemented for the first 2 doses and the first booster (dose 3), and a variant-adapted vaccine for subsequent booster doses with no additional changes to the vaccine product (i.e., no further updating). (A) Cumulative doses delivered per person over time, for a range of dose delivery strategies. In all strategies, the primary series was delivered to individuals 10 years and older, with scenarios of no additional doses; annual or 6-monthly boosters to the 75+ years population; annual or 6-monthly boosters to the 60+ years population; or annual boosters to the 10+ years population. (B) Mean infection-induced (pink dotted), vaccine-induced (orange dashed), and total (purple solid) IL over time for the “primary 10+, boost 60+ yearly” dose strategy. (C) Daily hospitalisations and (D) daily infections per million population for the 6 dose strategies, where the trajectory prior to vaccine introduction is shown in dark grey. (E) Total events (deaths, hospitalisations, and infection) per million population between 1 July 2022 and 31 December 2024 for each dose strategy. (F) Additional events averted per 100 additional doses over the same period relative to the “primary 10+, 3 doses only” dose strategy. Results for the scenario where no additional variant emergence occurs beyond Omicron (i.e., constant transmission and no additional immune escape) are shown in Fig D in S1 Text. HIC, high-income country; IL, immunity level.