Table 2. Concentration indices showing per capita benefits accruing to 148 countries and territories participating in the COVAX Facility, 23 January 2022.

Variable	Whole population					Population aged 65 years and older
	Wagstaff concentration index	Relative dose benefit, %a	Erreygers concentration index	Relative dose benefit, %b		Wagstaff concentration index	Relative dose benefit, %a	Erreygers concentration index	Relative dose benefit, %b
Vaccine doses allocated
Total benefits	−0.034	3	−0.022	2		−0.258	19	−0.176	13
Benefits to COVAX-sponsored countries	−0.657	49	−0.657	49		−0.577	43	−0.438	33
Benefits to self-financed COVAX-facilitated countries	0.214	16	0.089	7		0.057	4	0.031	2
Vaccine doses distributed
Total benefits	−0.014	1	−0.012	1		−0.248	19	−0.159	12
Benefits to COVAX-sponsored countries	−0.518	39	−0.507	38		−0.514	39	−0.338	25
Benefits to self-financed COVAX-facilitated countries	0.298	22	0.164	12		0.120	9	0.054	4

COVAX: COVID-19 Vaccines Global Access Facility; COVID-19: coronavirus disease 2019.

^a Relative dose benefits calculated from Wagstaff concentration index.

^b Relative dose benefits calculated from Erreygers concentration index.

Note: We analysed data for a total of 148 countries and territories: 88 countries qualifying for COVAX-sponsored vaccine doses under the advance market commitment mechanism and 60 countries self-financing their vaccine doses facilitated by COVAX. We calculated both Wagstaff and Erreygers concentration indices as the Erreygers index accounts for when data are categorical rather than continuous.²² An index of 0 to –1 means that the benefits from COVID-19 vaccines supplied by the COVAX Facility are higher for countries and territories with low incomes based on GDP per capita adjusted for PPP (pro-poor). When the concentration index is positive, it signifies a relatively pro-rich distribution of benefits, while when the concentration index is negative, it implies a relatively pro-poor distribution. Relative dose benefit is computed from the formula (CI*75) to interpret the concentration index. This is the amount that would need to be linearly transferred from the top (bottom) 50% to the bottom (top) 50% of countries based on GDP per capita PPP to obtain perfect equality in benefits. For a concentration index which is positive, the relative dose benefit is the percentage of excess doses allocated or distributed to the richest 50% countries relative to the poorest 50% countries. For a concentration index that is negative, the relative dose benefit is the percentage of excess doses allocated or distributed to the poorest 50% countries relative to the richest 50% countries.