2.1. Study Design
This research is a cross-sectional study.
2.2. Variables
Data6,7 showing the sum of A1AT PI*SZ and PI*ZZ genotypes numbers of countries in Europe and America were compared with the case and mortality numbers related to the COVID-19 pandemic as published by Worldometer13 on March 30, 2021 (Table 1, Table 2).
Since the A1AT PI*SZ and PI*ZZ data of countries other than Europe and America are insufficient and the numbers of COVID-19 pandemic cases and deaths in the Worldometer database were not considered reliable for each country, only the data of these two regions have been analyzed. In addition, Iceland from the European continent was excluded from the study due to the lack of data, and Russia was excluded because of the low reliability of the data as well as its geographical location in the Asian continent.