“…As population density is easier to calculate, most of them used this variable instead of other types of density. Based on our review, many studies conducted in countries such as the US ( Sarmadi et al, 2021 ; White and Hébert-Dufresne, 2020 ), Italy ( Ilardi et al, 2020 ), Iran ( Ahmadi et al, 2020 ), Bangladesh ( Sharif et al, 2021 ; Alam, 2021 ; Rahman et al, 2021 ), Oman ( Al Kindi et al, 2021 ), France ( Tchicaya et al, 2021 ), Nigeria ( Bayode et al, 2022 ) and Scotland ( Rideout et al, 2021 ) found population density as a positive and significant predictor of COVID-19 cases on state scale. However, about 40 % of studies reported that population density is not a significant factor to explain the difference in COVID-19 cases in different states ( Ramírez-Aldana et al, 2020 ; Gupta et al, 2020 ; Perone, 2021 ; Gargiulo et al, 2020 ; Basellini and Camarda, 2021 ; Pilkington et al, 2021 ; Sen-Crowe et al, 2021 ).…”