This chart shows the evolution over time in the revealed vaccine inequity (RVI) ratio by World Bank income classification.
The RVI ratio is defined as the global vaccine share over the global population share. If an income group achieves an RVI > 1 (or < 1), then we note that the group has been able to administer an “excess” (“shortage”) of vaccines relative to its population size and relative to the counterfactual of an equal global distribution. In this specific context where we compare vaccine distribution with the distribution of need as measured by the total population, vaccine inequity is revealed to the extent that the indicator shows deviations from 1. Note that the RVI concept is loosely inspired by the Revealed Comparative Advantage concept in international trade.
The vaccine share refers to the share in total vaccinations globally. Total vaccinations are defined as adjusted primary doses + boosters. Primary doses pertain to the initial vaccination cycle and are adjusted to take into account the diversity of vaccine protocols. Primary doses of 1- and 3-dose vaccines are adjusted into 2-dose equivalents, which amounts to multiplying them by 2 and 2/3, respectively, before adding them up. This method, further detailed in this post, makes sure that we make correct comparisons across countries and country groups in the doses space.