International Journal of Preventive Medicine (Int J Prev Med)2008-780214420230508Why Did the Use of the Mask not Control the Infection Caused by COVID‑19 in the World? Where is the Missing Loop?28042804ENCellular and Molecular Research Center, Gerash University of Medical Sciences, Gerash20230508Dear Editor, The spread of COVID-19 in December 2019 and the spread of this infection led to a global epidemic, and as of October 26, 2021, more than 243 million confirmed infected cases, and over 4953,246 deaths were reported globally.http://ijpm.mui.ac.ir/index.php/ijpm/article/view/2804http://ijpm.mui.ac.ir/index.php/ijpm/article/download/2804/717718645