“…All included studies were carried out in the pre-vaccinal period: between February and July 2020 for studies published in 2020, and until November 2020 for those published in 2021. Eleven of the 23 studies were carried out in Europe [ 18 , 24 , 26 , 27 , 28 , 29 , 34 , 36 , 40 , 42 , 43 ], of which five were in the United Kingdom [ 24 , 26 , 34 , 36 , 43 ], nine studies in America [ 23 , 25 , 30 , 31 , 32 , 35 , 37 , 39 , 41 ], of which seven were in the USA [ 23 , 25 , 30 , 31 , 32 , 35 , 39 ], and only three in Asia (Saudi Arabia, Iraq and Iran) [ 22 , 33 , 38 ].…”