Morbidity and mortality from COVID-19. The problem of data comparability

Abstract

The numbers of COVID-19 cases and deaths are currently attracting worldwide attention. Different web resources publish these data for countries and their regions. The data are available to everyone and are updated in almost real-time mode. The rapid collection of data on cases and deaths and the open access of these data clearly provide important advantages in combating the epidemic, predicting its spread, and planning containment measures. An important area of research on the COVID-19 epidemic is the comparison of countries and territories by their levels of morbidity, lethality, and mortality. Given the opportunities opening up today for data analysis, it is crucially important to understand according to what criteria the data are collected.

This paper discusses the key issues of collecting data on COVID-19 cases and deaths and raises the question of data comparability across countries. It shows that countries differ significantly in their approaches to reporting COVID-19 cases and deaths. The data comparability across countries can be influenced, among other things, by the availability of tests, the criteria adopted by the country for testing for the virus (both while the patient is alive and post-mortem), and approaches to determining the cause of death and recording COVID-19 deaths in those with pre-existing chronic conditions. Different approaches to recording COVID-19 cases and deaths across countries, as well as their changes over time, pose significant limitations to our ability to assess the spread of the epidemic. These limitations should be taken into account when performing the analysis of COVID-19 morbidity and mortality. Ignoring these limitations can significantly distort our understanding of the spread of the epidemic across different territories.