The effect of outcome choice on vaccine dose allocation: a modelling study

Area of Science:

• Epidemiology
• Public Health
• Mathematical Modeling

Background:

• Pandemic vaccine rollout strategies often prioritize healthcare burden or mortality, not quality-adjusted life-years (QALYs).
• COVID-19 vaccine distribution models typically focus on reducing deaths.

Purpose of the Study:

• To investigate how prioritizing life-years saved, rather than deaths averted, impacts optimal COVID-19 vaccine allocation strategies.
• To compare the effectiveness of single-dose versus two-dose vaccine prioritization.

Main Methods:

• Extended a mathematical model to estimate life-years saved and deaths averted for one-dose and two-dose COVID-19 vaccination schedules in England.
• Incorporated updated COVID-19 mortality risk data and population-specific vaccine uptake levels.

Main Results:

• Optimal vaccine dose allocation strategy varied based on the outcome measure (deaths vs. life-years).
• For fewer than ten million doses, a single-dose strategy was consistently more beneficial.
• Above ten million doses, a two-dose strategy became optimal, influenced by vaccine effectiveness and chosen outcome.

Conclusions:

• Focusing on life-years saved can identify different optimal vaccination policies compared to focusing solely on deaths.
• Life-years lost should be considered a primary metric for disease impact alongside infections, hospitalizations, and deaths in future vaccine programs.