Abstract
Relation between the epidemic size of COVID-19 and the population size was examined for 184 countries in different regions in the world. The plot of the number of the patients or that of the deaths against the population size revealed that the number of the patients or the deaths and the population size were correlated with correlation coefficient 0.5~0.9 within regions but not necessarily across regions; In African region, the correlation emerged only when the region was further divided into sub-regions used by UN Statistics Division. The case-fatality rate was ~0.01 for all the regions or sub-regions. In American and European regions where alpha-1 antitrypsin (AAT) deficiency is prevalent, the number of patients or deaths per population was ~10-fold higher than in the other regions. Analysis indicated that clustering of population with AAT deficiency was necessary for large outbreak to occur.
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