Which countries need COVID-19 vaccines the most? Development of a prioritisation tool

The COVID-19 pandemic and associated non-pharmaceutical interventions (NPIs) have affected all countries. With a scarcity of COVID-19 vaccines there has been a need to prioritize populations, but assessing relative needs has been challenging. The COVAX Facility allocates vaccines to cover 20% of each national population, followed by a needs assessment that considers five quantitative metrics alongside a qualitative assessment. The objective of this study was to identify the most important factors for assessing countries' needs for vaccines, and to weight each, generating a scoring tool for prioritising countries.

The study was conducted between March and November 2021. The first stage involved an online Delphi survey with a purposive and snowball sample of public health experts, to reach consensus on country-level factors for assessing relative needs for COVID-19 vaccines. The second stage involved a discrete choice experiment (DCE) to determine weights for the most important factors.

Responses were received from 28 experts working across 13 different countries and globally. The most common job titles reported were director and professor, with most based in national public health institutes (n = 9) and universities (n = 8). The Delphi survey found 37 distinct factors related to needs. Nine of the most important factors were included in the DCE. Among these, the most important factor was the 'proportion of overall population not fully vaccinated' (with a mean weight of 19.5), followed by 'proportion of high-risk population not fully vaccinated' (16.1), 'health system capacity' (14.2), 'capacity to purchase vaccines' (11.9) and the 'proportion of the population clinically vulnerable' (11.3).

Several factors exist, extending beyond those currently used, which may lead to some countries having a greater need for vaccines compared to others. By assessing relative needs, this scoring tool can build on existing methods to further the role of equity in global COVID-19 vaccine allocation.