COVID-19 Vaccine Allocation: Modeling Health Outcomes and Equity Implications of Alternative Strategies

Abstract

Given the scarcity of safe and effective COVID-19 vaccines, a chief policy question is how to allocate them among different sociodemographic groups. This paper evaluates COVID-19 vaccine prioritization strategies proposed to date, focusing on their stated goals; the mechanisms through which the selected allocations affect the course and burden of the pandemic; and the main epidemiological, economic, logistical, and political issues that arise when setting the prioritization strategy. The paper uses a simple, age-stratified susceptible-exposed-infectious-recovered model to quantitatively assess the performance of alternative prioritization strategies with respect to avoided deaths, avoided infections, and life-years gained. We demonstrate that prioritizing essential workers is a viable strategy for reducing the number of cases and years of life lost, while the largest reduction in deaths is achieved by prioritizing older adults in most scenarios, even if the vaccine is effective at blocking viral transmission. Uncertainty regarding this property and potential delays in dose delivery reinforce the call for prioritizing older adults. Additionally, we investigate the strength of the equity motive that would support an allocation strategy attaching absolute priority to essential workers for a vaccine that reduces infection-fatality risk.

COVID-19 Sex-Age Mortality Modeling - A Use Case of Risk-Based Vaccine Prioritization

“…An important question is how to prioritize different strata of the population to minimize the risks to the public as a whole. Ferranna et al (2021) compiled a table of various goals stated by government institutions that are in charge of setting policies and priorities for vaccine allocation in individual countries (US, UK) and worldwide (WHO). Such goals vary from the more obvious 'reduce mortality" to the less e.g., "reduce negative societal impact, mitigate of health inequities, treat people fairly, minimize impact".…”

“…Such goals vary from the more obvious 'reduce mortality" to the less e.g., "reduce negative societal impact, mitigate of health inequities, treat people fairly, minimize impact". Based on the goals stated above certain countries would choose to prioritize higher certain occupations, e.g., high-risk health workers and first responders, personnel in long-term facilities, racial or ethnical minority status of population groups, their socioeconomical vulnerability etc., (Ferranna et al, 2021). Out of all possible considerations our approach aims at minimizing the overall mortality based on age and sex, while respecting other considerations and leaving it up to the policymakers to apply our recommendations selectively.…”

“…Many US states are implementing more granular age cutoffs. • Four in Germany: "80+", "70-79", "60-69", "<60" (Cylus 2021) • Eight age-based tiers in the UK: "80+", " 75-79", "70-74", "65-69", "60-64", "55-59", "50-54", "<50" (Priority Groups 2020, Ferranna et al, 2021. • "Israel's initial age cut-off of 60 years and over… Estonia focuses first on those 70 years and over" (Cylus 2021).…”

“…A typical COVID-19 age-based unisex vaccination campaign would typically roll out as a sequence of the age-cutoff phases that would decline by 5 or 10 years at each phase (Ferranna et al, 2021, Priority Groups 2020, Cylus 2021). One such possible sequence of phases is shown in Table 5.…”

“…The latter concept facilitates solving such a practical problem as the COVID-19 mortality risk-based vaccine prioritization of population strata based on age and sex in a fashion tailored to a given country, see Chapter 2.4.3. Out of several popular vaccine allocation criteria, see (Ferranna et al, 2021) ours is to decrease mortality as much as possible.…”