en عمومى General مروری Review <span style="font-size:12pt"><span style="line-height:115%"><span style="font-family:&quot;Times New Roman&quot;,serif">Coronavirus disease 2019 (COVID-19), a contagious&nbsp;illness, has been quickly spreading throughout the world and continues to pose a danger to public health on a worldwide scale. It is essential to diagnose potentially serious or critical patients immediately and provide targeted patients with prompt therapy because patients with critical or severe cases have poor prognoses. Current biomarkers cannot reliably predict the severity of COVID-19 infection; thus, we need surrogate indicators to determine the severity of COVID-19 and forecast its progression. The neutrophil-to-lymphocyte ratio (NLR) is a new biomarker that has been linked to inflammation and prognosis in a variety of diseases. In this narrative review, we investigated the NLR&#39;s diagnostic and prognostic validity in patients with COVID-19 infection.</span></span></span><br> &nbsp; Neutrophil-to-lymphocyte ratio, COVID-19, Coronavirus, Diagnosis, Prognosis 67 81 http://intjmi.com/browse.php?a_code=A-10-1-566&slc_lang=en&sid=1 Danial Soltani 10031947532846006396 10031947532846006396 No Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Amirhossein Mohammadzadeh 10031947532846006397 10031947532846006397 No Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Behnaz Hatami 10031947532846006398 10031947532846006398 Yes Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.