This chart shows the evolution over time of the distribution of daily COVID-19 cases across World Bank income groups. It calculates for each region the share in daily COVID-19 cases globally. To remove intra-week volatility in the reported data, the share is transformed into a 7-day trailing average by dividing the 7-day trailing averages of the numerator and denominator (7-day trailing average refers to the average value of the latest observation and the preceding 6 days).
The indicator reflects an absolute concept in that it expresses how the absolute case tally in a particular region contributes to the global case tally. This differs fundamentally from the concept of the case rate, which expresses the absolute tally relative to population size and thus provides an indication of performance controlling for population size.
It should be noted that the different income groups shown here are of very different population size dimensions. The global population as per the 2021 medium-variant projection of World Population Prospects is 7,866 million people, which is distributed as follows:
Low-income countries (LICs): 683 million
In light of these differences in population size, we expect large differences in the distribution of absolute cases even if case rates were constant across groups.
Finally, it should be noted that limitations to testing will mean that the number of confirmed cases is lower than the true number of infections.