Factors associated with case fatality in COVID-19

Abstract

Introduction: The ability of the novel coronavirus SARS-CoV-2 to selectively target high-income countries, has puzzled many epidemiologists. Several possible protective factors such as Bacillus Calmette–Guérin (BCG) vaccine coverage, higher environmental temperature, higher proportion of the younger population, prevalence of hypertension (HTN), diabetes, and smoking have been suggested. This study aims at understanding the influence of each of these factors on case fatality rate due to COVID-19. Methods: We selected two or more countries in each geographical region, which were severely affected by SARS-CoV-2 infections. Case fatality rate for each country was calculated obtaining data on the number of cases and deaths in each country. The details of coverage of BCG vaccination, prevalence of HTN and diabetes, age structure of the population, and average maximum and minimum temperatures during February and March months of 2020, and prevalence of smoking for each country were taken from the World Health Organization and other standard databases till May 9, 2020. Statistical analysis was done using Karl Pearson's correlation and multiple linear regression model. Results: Case fatality rate was negatively correlated with BCG coverage of the country, percentage of population below 14 years age and average maximum temperatures. Conclusions: Environmental temperature, wider BCG coverage, and higher proportion of the younger population in middle- and low-income countries might have played a protective role against COVID-19.

Keywords

• bacillus calmette–guerin
• covid-19
• temperature
• young age