This chart traces the evolution over time of the share of countries that have started administering boosters in the total number of countries within each country group of the World Bank income classification.
The definition of the country universe matters considerably for this chart. We consider a total of 196 countries. This universe is based on the World Bank’s Fiscal Year 2022 income classification (see full details in the background section below) and reflects a further narrowing down to only include members and/or observers of UN or UN specialized agencies (which excludes 21 HICs and 1 UMIC, which are mostly overseas territories and dependencies). The full methodology is discussed in detail in the background notes copied below.
Pandem-ic uses the World Bank income classification as a major building block in the analysis of the impact of the pandemic.
The income classification groups countries in four buckets by per capita income levels: high-income countries (HICs), upper-middle-income countries (UMICs), lower-middle-income countries (LMICs) and low-income countries (LICs). We use the current FY2022 classification, which determines the thresholds of the buckets as follows:
See here for a dynamic visualization of how the income classification of countries has changed over time through the current FY2022 classification
A good part of this site also analyzes the pandemic by region (where we use the World Bank regional classification and the UN geo-scheme of subregions). In both cases (i.e. across income groups and regions), the universe of countries is based on the World Bank income classification. More on that in the next note.
The universe of countries on this website is determined as follows.
Note that the vaccination data is pulled from Our World in Data, which utilizes a slightly different universe of locations. In sticking with the above 196 countries and economies, we have made the following adjustments relative to the OWID universe.
For each of the above adjustments to the vaccination data, we make adjustments to the demographic data that vaccine information is related to (including population size, age structure and priority group size).
Finally, note that no adjustments are required to the totals for France as its overseas territories and dependencies are already included.
Most of the vaccine data on this site converts the doses that have been administered into "double-dose equivalents" (DDEs). That is because the vaccine landscape is diverse with different treatment protocols, Most vaccines require 2 doses but there are some that require just 1 (e.g. CanSino, Johnson & Johnson and the stand-alone version of Soberana Plus) and others that require 3 (Abdala, the combination of Soberana 2 & Soberana Plus and ZF2001). These are considered primary vaccinations which when completed result in full vaccination status - they are not boosters. Given this diversity of protocols, we would like to bring them all into a common denominator so that doses administered can be compared properly. On this site, we choose double-dose vaccines as the common denominator.
Converting into DDEs means that we multiply the number of single doses administered by 2 for a single-dose protocol and 2/3 for a three-dose protocol. For example, if a country had administered 100 doses under a single-dose protocol, we would count it as 200. Conversely, if a country had administered 300 doses under a three-dose protocol, the number of doses would be scaled down to 200. In both cases, we would achieve full vaccination at 200 DDE doses per 100 people.
Why not just sum up unadjusted doses?
That would lead to two problems:
The DDE adjustments tackles these 2 problems. Thanks to the adjustment, we can compare countries's progress regardless of the mix of vaccines they are using. We also have a common threshold of full vaccination at 200 doses per 100 people or 200%. Moreover, this threshold is invariant across countries and over time. It is a steady milestone against which progress can be evaluated.
If the DDE approach allows us to measure progress towards full vaccination, what is the difference then with alternative measures such as the share of the total population that is fully vaccinated? The answer is that the DDE approach is less demanding in terms of the data that is required. In order to calculate the full vaccination rate (the share of the total population that is fully vaccinated), we need to have timely information on whether each dose administered contributes to the start, the completion or both of a vaccination cycle (both would be the case of a single-dose protocol). The DDE approach requires information about single versus multiple dose vaccinations, but it is agnostic and therefore less demanding about whether a dose of a multiple-dose vaccine represents full or partial vaccination. That is a major advantage given that for several countries such data is not available on a timely basis (see methodological annex here for a full discussion).
Note on Cuban vaccines and data: Cuba currently administers different protocols: Abdala (3-dose vaccine), Soberana 2 combined with Soberana Plus (considered a 3-dose vaccine for children) and Soberana Plus stand-alone (considered a 1-dose vaccine for those with prior COVID). Based on this distinction, we derive from the data published by the Cuban authorities that total doses under 1-dose protocol (Soberana Plus stand-alone) equal the difference between people fully vaccinated and people vaccinated with three shots. Total doses under 3-dose protocols are therefore total doses administered minus doses administered under the 1-dose protocol.
China publishes on a daily basis the total number of doses administered, but this includes both primary vaccine doses and booster doses. Data on booster doses are not published on a daily basis. For this reason the data presented on the website incorporate the following adjustments to complete the primary and booster vaccination series for China. Note that these adjustments are made to the data for mainland China, which are afterwards aggregated with those of Macao SAR and Hong Kong SAR.
First, the earliest datapoint for boosters in mainland China is for November 5, 2021: 37 million. Since we don't have a clear anchor point for the actual starting point of the series, we assume that November 5 is also the starting point of the underlying booster program - an assumption which abstracts from reality but may be relatively innocuous given the "small" size of the number relative to the total population.
Second, we interpolate the data on days between published data points. For example, China published data on boosters on November 5 and 12. For the days in between, we interpolated the data on boosters as follows. We first calculated the ratio of the change in total vaccinations to the change in total boosters. We then multiplied this ratio with the daily observed change in total vaccinations, which approximates the daily increments in boosters based on the share of boosters in total vaccinations over the entire period and the daily change in total vaccinations. We then calculated the cumulative sum of the daily increments in boosters to arrive at the evolving stock of boosters.
Third, we extrapolate the data for the most recent days where we have information on total vaccinations but no information yet on total boosters, so that there is no anchor point as in the interpolation. For this reason, we use the ratio of the change in total vaccinations to the change in total boosters of the most recent period for which we have two observations of both variables. In other words, if 70% of new vaccinations between November 5 and 12 were boosters, then we would apply that ratio to the the daily changes in vaccinations after November 12 assuming that after November 12 there are no data points on total boosters (just an example as China did irregularly update the booster information afterwards).
The distribution of vaccine doses across countries is described on the basis of data on the actual doses administered. The reasons why the numbers may be low can vary widely and include international vs domestic factors as well as supply versus demand factors. At this moment in time, however, the most likely reason for low numbers is related to international supply bottlenecks.
The charts that describe vaccine sufficiency for the priority group do not measure actual vaccination of the priority group. That is currently impossible to consistently assess at the global level given data gaps. Instead, it describes, on the basis of the size of the priority group and the number of doses administered, the extent to which the priority group could have been covered through the vaccination efforts up through the latest available data point.
The vaccine sufficiency measure would approximate actual vaccination if governments act as “benevolent social planners” interested in vaccinating their most vulnerable groups first. Even if that is the case, discrepancies may arise as it also requires common agreement about who the most vulnerable groups are. The charts assume that the vulnerable group consists of medical professionals under 60 and the entire 60+ population. In practice, governments around the world define their priority group in many different ways. The definition on this site is a minimal one in the interest of cross-country comparability and data availability.
How do we calculate the size of the priority group?
More refined estimates of the health workforce will undoubtedly be available at the country level. In the interest of building a global dataset we rely however on this method which has the advantage of imposing transparent assumptions on all countries in an equal way.
Several visualizations distinguish between the extensive and intensive margins of vaccination progress. The extensive margin captures the extent to which countries are participating in vaccination efforts. In the polar bar charts on this website, this can be observed in the circular progress bar, which shows the share of countries, by income group, that report nonzero vaccination data. The visualization also colors the country codes of countries in the outer circle according to whether positive vaccination data is being reported (blue means yes; grey means no).
The intensive margin measures vaccination progress within countries. In the polar bar visualizations, the outward-oriented bars capture the efforts of countries to raise the coverage ratio to the maximum of 200 (on the vertical axis).