This chart shows the evolution over time of the booster sufficiency ratio for the priority group by World Bank income group.
The ratio is defined as the total number of booster doses that have been administered to the total population divided by the size of the priority group in that population. The priority group includes all seniors aged above 60 and all health workers (physicians, nurses and midwives) below 60 – the latter age cut-off to avoid double counting. For further details on the concept and measurement of the priority group, see the note on the priority group in the background section below.
Note that booster sufficiency for the priority group does not measure actual vaccination of the priority group.
It therefore measures, in a minimalistic way, whether the a proxy for the supply of vaccines (the total booster doses administered to the total population thus far) could have been sufficient to cover fully the priority group.
Finally, the booster sufficiency ratio is censored at 100. Once the priority group can be fully covered with boosters administered, we consider that vaccine sufficiency (in the minimal sense of the concept) has been attained. Larger values are set at 100.