International Journal of Preventive Medicine (Int J Prev Med)2008-780212122022011725832583ENDepartment of Health Information Management, School of Allied Medical Sciences, Tehran University of Medical Sciences, TehranSocial Determinants of Health Research Center, Alborz University of Medical Sciences, KarajChronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Endocrinology and Metabolism Research Institute, Tehran University of Medical Sciences, TehranDepartment of Medical Emergencies, Qom University of Medical Sciences, QomDietary Supplements and Probiotic Research Center, Alborz University of Medical Sciences, KarajCenter of Maritime Health and Society, Department of Public Health, University of Southern Denmark, EsbjergNon‑communicable Diseases Research Center, Alborz University of Medical Sciences, Karaj & Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran20220117Background: Evidence showed that partial or complete loss of smell and taste might be a possible primary symptom of the 2019 novel coronavirus (COVID‑19). This study aimed to systematically review and pool all available evidence on the olfactory and gustatory dysfunction in COVID‑19 patients. Methods: In this systematic review, a comprehensive search was carried out systematically through e‑databases including PubMed, EMBASE, Scopus, and Web of Science (WoS); that was limited to English‑language studies published from 2019 up to 6th May 2020. Afterward, all studies reported the taste and smell dysfunction in the COVID‑19 patients were included. The quality of the studies was assessed by the Mixed Methods Appraisal Tool (MMAT). The pooled prevalence of olfactory and gustatory dysfunction was estimated using the random effects meta‑analysis method. Results: Among 28 eligible included studies in this systematic review, finally, 22 studies met the eligibility criteria and were included in the meta‑analysis. According to the random effect meta‑analysis, the global pooled prevalence (95% confidence interval) of any olfactory dysfunction, anosmia, and hyposmia was 55% (40%‑70%), 40% (22%‑57%), and 40% (20%‑61%) respectively. The pooled estimated prevalence of any gustatory dysfunction, ageusia, and dysgeusia was 41% (23%‑59%), 31% (3%‑59%), and 34% (19%‑48%) respectively. Conclusions: Olfactory and gustatory dysfunction is prevalent among COVID‑19 patients. Therefore, olfactory and gustatory dysfunction seems to be part of important symptoms and notify for the diagnosis of COVID‑19, especially in the early phase of the infection.http://ijpm.mui.ac.ir/index.php/ijpm/article/view/2583http://ijpm.mui.ac.ir/index.php/ijpm/article/download/2583/717718423