Supplementary details including further mathematical description of the model and parameters.

Fig A. Schematic diagram illustrating the COVID-19 vaccine allocation algorithm. Fig B. Modelled trajectories of the reproduction number R_t over time. Fig C. Exemplar demographic patterns for each of the 2 income settings. Fig D. Impact of vaccination in a high-income country setting with substantial prior transmission and high vaccine access, assuming no additional variant emergence beyond Omicron (i.e., constant transmission and no additional immune escape, or no “drift”). Fig E. Impact of vaccination in a lower-middle-income country setting with substantial prior transmission and moderate vaccine access, assuming no additional variant emergence beyond Omicron (i.e., constant transmission and no additional immune escape, or no “drift”). Fig F. Impact of vaccination in a high-income country setting with minimal prior transmission and high vaccine access (Category 3). 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. Fig G. Impact of vaccination in a low-middle-income country setting with substantial prior transmission and low vaccine access, where individuals 40+ years are initially targeted. Fig H. Impact of vaccination in a lower-middle-income country setting with substantial prior transmission and moderate vaccine access (Category 2), assuming WHO coverage targets. Fig I. Comparison of vaccine impact for different ancestral and variant-adapted vaccine scenarios for the lower-middle-income country setting with substantial prior transmission (Category 2). Fig J. Comparison of vaccine impact for different ancestral and variant-adapted vaccine scenarios for the high-income country setting with minimal prior transmission (Category 3). Fig K. Impact of vaccination in future scenarios where an additional variant of concern emerges from 1 October 2022, in a high-income setting with minimal prior transmission and high vaccine access (Category 3). We assume a variant-adapted vaccine is implemented from dose 4. Fig L. Sensitivity of the model output to the level of “drift” in a high-income setting with substantial prior transmission (Category 1). Fig M. Sensitivity of model results to assumptions regarding the level of protection afforded by infection in a high-income setting with substantial prior transmission (Category 1). Fig N. Sensitivity of model results to the decay rate of protection following recovery from SARS-CoV-2 infection in a high-income setting with substantial prior transmission (Category 1). Table A. Prior and posterior parameter estimates for the immunological model. Table B. Transmission model state transitions. Table C. Transmission parameter description and values. Table D. Default scenarios and assumptions for vaccine uptake within targeted age groups for each of the 2 income settings. Table E. Default scenarios and assumptions for the 3 broad modelled categories of country and epidemiological state. Table F. Total doses delivered, infections, hospitalisations, and deaths for each of the Category 1 and 3 settings, for a range of vaccine dose strategies and variant scenarios. 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. Table G. Total doses delivered, infections, hospitalisations, and deaths for each of the Category 1 and 3 settings, for a range of vaccine dose strategies and variant scenarios. We assume no additional variant emergence beyond Omicron (i.e., constant transmission and no additional immune escape, or no “drift”). Table H. Total doses delivered, infections, hospitalisations, and deaths for the Category 2 setting, for a range of vaccine dose strategies and variant scenarios. We assume AZD1222 is implemented for the first 2 doses, mRNA-1273 for the first booster (dose 3), and a variant-adapted vaccine for subsequent booster doses (doses 4 and 5). Table I. Total doses delivered, infections, hospitalisations, and deaths for the Category 2 setting, for a range of vaccine dose strategies and variant scenarios. We assume no additional variant emergence beyond Omicron (i.e., constant transmission and no additional immune escape, or no “drift”). Table J. Total doses delivered, infections, hospitalisations, and deaths for the Category 2 setting, for a range of vaccine dose strategies and variant scenarios, assuming the WHO coverage target assumption. We assume AZD1222 is implemented for the first 2 doses, mRNA-1273 for the first booster (dose 3), and a variant-adapted vaccine for subsequent booster doses (doses 4 and 5). Table K. Total additional infections, hospitalisations, and deaths averted, and total additional vaccine doses delivered for the Category 1 and 3 settings. We assume no additional variant emergence beyond Omicron (i.e., constant transmission and no additional immune escape, or no “drift”). Table L. Total additional infections, hospitalisations, and deaths averted, and total additional vaccine doses delivered for the Category 2 setting. We assume no additional variant emergence beyond Omicron (i.e., constant transmission and no additional immune escape, or no “drift”). Table M. Total doses delivered, infections, hospitalisations, and deaths for the Category 2 setting, for a range of vaccine dose strategies, for the scenario where individuals 40+ years are initially targeted. We assume AZD1222 is administered for all doses. Table N. Total doses delivered, infections, hospitalisations, and deaths for different ancestral, variant-adapted, and yearly updated vaccine scenarios. Table O. Impact of vaccination in future scenarios where an additional variant of concern emerges from 1 October 2023.

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