As SARS-CoV-2 spread rapidly around the world, it became clear that equitable access to vaccines against the virus had to be the linchpin of an effective global response. In past pandemics, including H1N1 in 2009, delays in access to essential health products were due in part to the lack of a global allocation mechanism that could distribute these products. In a bid to learn from past mistakes and allocate Covid vaccines equitably, CEPI, Gavi, and WHO in April 2020 launched COVAX—the vaccine pillar of the Access to COVID-19 Tools (ACT) Accelerator—forming a global procurement framework to supply Covid vaccines to countries worldwide. The effort was backed by the COVAX Advance Market Commitment (AMC) financing mechanism, which was designed to ensure that 92 low-income countries unable to purchase vaccines on the open market could get them for free. The task was monumental: COVAX was to be the largest vaccine procurement and supply operation in history.
Designing the algorithm
Through a Gates Foundation-funded grant, Linksbridge data scientists worked under the guidance of Gavi and WHO to create an algorithm that would allocate Covid vaccine doses according to COVAX’s main priorities: contain the pandemic and ensure equitable access to all participating countries. With these priorities in mind, COVAX established a two-phase allocation framework. Phase 1 sought to allocate vaccine doses equally among participating countries—to increase coverage for all countries at the same rate—while doses in Phase 2 would be allocated according to a country’s need and their capacity to receive, store, distribute, and administer doses.
Our team designed the algorithm to follow a complex set of rules outlined in the allocation framework, including constraints related to supply availability and country infrastructure, timing between doses, and the number of doses each country should receive—all while maximizing equity and country preferences.
Doses allocated, lives saved
When our team began developing the algorithm in October 2020, over 2 million new Covid cases were being reported each week. The pandemic was raging, and time was of the essence. In just eight weeks, Linksbridge data scientists—working with partners from WHO’s Joint Allocation Taskforce and the Independent Allocation Vaccines Group—delivered an algorithm and API connection for test allocation runs. By January 2021, the algorithm successfully allocated the first vaccine doses through the COVAX Facility. The next month, Ghana became the first country to receive Covid vaccines from COVAX—marking the beginning of the global rollout and the first time in history that pandemic vaccines would be distributed to LMICs in a coordinated way. Altogether, the Linksbridge-developed algorithm helped allocate nearly 1 billion vaccine doses through 12 distribution rounds in 2021, saving an estimated 857,000 lives in AMC countries.
A description and review of the allocation process was published in the Oxford Review of Economic Policy.
