The objectives of this research were to produce a macro-level overview of the global COVID-19 burden and estimate the value of access to COVID-19 vaccines. A targeted literature review collated evidence of the burden. Linear modelling and data analysis estimated the health and economic effects of COVID-19 vaccines delivered in 2021, and whether additional value could have been achieved with broader and more equitable access. By 1 December 2020, there had been an estimated 17 million excess deaths due to COVID-19. Low-income countries allocated more than 30% of their healthcare budgets to COVID-19, compared to 8% in high-income countries. All country income groups experienced gross domestic product (GDP) growth lower than predicted in 2020. If all 92 countries eligible for COVAX Advance Market Committee (AMC), access had reached 40% vaccination coverage in 2021, 120% more excess deaths would have been averted, equivalent to USD 5 billion (10⁹) in savings to healthcare systems. Every USD spent by advanced economies on vaccinations for less advanced economies averted USD 28 of economic losses in advanced economies and USD 29 in less advanced economies. The cost to high-income countries when not all countries are vaccinated far outweighs the cost of manufacturing and distributing vaccines globally.

This exploratory qualitative study involved semi-structured interviews with adults and caregivers of adults at high risk of severe COVID-19, addressing current COVID-19 avoidance and protective behaviors and how these behaviors impacted their lives. Results were interpreted in a separate think tank session. Insights were developed into a conceptual model of COVID-19 avoidance and protective behaviors and the associated impacts on health-related quality of life and overall functioning. Data were interpreted using a hybrid inductive and deductive thematic analysis. Twelve high-risk individuals and two caregivers were interviewed across four focus groups (April–July 2022). Major behavioral themes included physical distancing, physical and medical protection, quality of support services and networks, and information to make decisions. Major impacts included family, social, and emotional functioning; work and finances; and healthcare access. The final conceptual model comprised 13 behaviors to avoid COVID-19 categorized within four themes, and 13 impacts within five themes. Individuals at high risk of severe COVID-19 and their caregivers continue practicing COVID-19 avoidance behaviors post-lockdown and feel left behind by the general population. Our conceptual model may be used to inform health authorities and other governing bodies’ decisions in executing strategies aimed at improving these individuals’ lives.

Healthcare decision-makers face difficult decisions regarding COVID-19 booster selection given limited budgets and the need to maximize healthcare gain. A constrained optimization (CO) model was developed to identify booster allocation strategies that minimize bed-days by varying the proportion of the eligible population receiving different boosters, stratified by age, and given limited healthcare expenditure. Three booster options were included: B₁, costing US $1 per dose, B₂, costing US $2, and no booster (NB), costing US $0. B₁ and B₂ were assumed to be 55%/75% effective against mild/moderate COVID-19, respectively, and 90% effective against severe/critical COVID-19. Healthcare expenditure was limited to US$2.10 per person; the minimum expected expense using B_1, B_2, or NB for all. Brazil was the base-case country. The model demonstrated that B₁ for those aged <70 years and B₂ for those ≥70 years were optimal for minimizing bed-days. Compared with NB, bed-days were reduced by 75%, hospital admissions by 68%, and intensive care unit admissions by 90%. Total costs were reduced by 60% with medical resource use reduced by 81%. This illustrates that the CO model can be used by healthcare decision-makers to implement vaccine booster allocation strategies that provide the best healthcare outcomes in a broad range of contexts.