 We also analyzed the possible existence of a bias: countries with low GDP-per capita , typically located in warm regions, might have less intense testing and we discuss correlation with the above variables.
<clarity>  We also analyzed the possible existence of a bias: countries with low GDP-per capita , typically located in warm regions, might have less intense testing and we discuss correlation with the above variables.
 We also analyzed the possible existence of a bias: countries with low GDP-per capita might have less intense testing and we discuss correlation with the above variables.