Monitoring trends and differences in COVID-19 case fatality rates using decomposition methods: Contributions of age structure and age-specific fatality

Christian Dudel; Tim Riffe; Enrique Acosta; Alyson A. van Raalte; Mikko Myrskyla

The data we use is provided in different age groups, depending on the country. The following age groups are used in the original data for both case counts and death counts: For the decomposition, the age groups have to match. This is the case for China, Spain, South Korea, and Italy; in case of the latter the age categories 80-89 and 90+ have to be merged. The age groups provided for France, Germany, and the United States are problematic, as they do not match the age groups of any other country. Aggregating the age groups, as for Italy, does not help, either. For instance, the age category of 15 years to 44 years available for France cannot be created based on the German data. To deal with this issue, we adjusted the case counts and death counts for France, Germany, and the United States using a smoothing approach, which is able to estimate counts for age groups 0-9, 10-19, …, 80+ [9] .