Introduction
Coronavirus disease‐2019 (COVID‐19), caused by the severe acute respiratory syndrome‐coronavirus 2 (SARS‐CoV‐2) is cause of illness and death of millions since December 2019. It is a highly contagious disease that spreads via contact and aerosol transmission. There are much more cases than reported because many are asymptomatic but infectious. Gold standart diagnostic tool is testing nasopharyngeal swab samples by real‐time reverse‐transcription polymerase chain reaction (PCR). But PCR is not available in every health-care institution due to its cost and working technique, elsemore getting results takes time. Computed tomography (CT) of the chest is indicated in those patients suspicious of pneumonia with a prior chest x-ray that is undiagnostic. CT is expensive, not available in every healthcare institution and patients are exposed to radiation. There is a need for fast diagnostic parameters to assist doctors in the diagnostic phase and to help differentiating patients with Covid-19 pneumonia than those without. Comlpete blood parameters are studied in many patients at admittion in Covid-19 clinics. Biomarkers of inflammation derived from the peripheral blood, hemogram parameters such as white blood cell (WBC) count, neutrophil lymphocyte ratio (NLR) and platelet lymphocyte ratio (PLR) have been investigated as independent predictors for prognosis of systematic inflammatory diseases 1. Monocyte-macrophage activation markers are increased and correlate with other inflammatory markers in SARS-CoV-2 infection, in association to hospital admission. The red blood cell distribution width (RDW) is a measure of the variation of red blood cell volume. There are recent studies focusing on RDW 2. Mean platelet volume (MPV) is one of the platelet function indices which reflects the platelet production rate and stimulation 3. Platelet distribution width (PDW) is a direct measure of platelet size variation and a  marker of platelet activation. High levels of PDW have been associated with Covid-19 mortality 4. All above mentioned parameters are studied by routine complete blood count test that might be overlooked by clinicians. The major difficulty for physicians is to translate the recommended guidelines into clinical practice. In this study we aimed to determine wheather monocyte levels, eosinophil levels, MPV, PDW, RDW, NRL, MLR and PLR can be used as biomarkers in the early diagnosis of laboratory-confirmed COVID-19 patients as well as to explore the most useful diagnostic biomarkers and optimal cut-off values. Else more to investigate if these parameters can be used in differentiation of Covid-19 patients with pneumonia than those without and healthy controls. To the best of our knowledge this is the first study investigating above mentioned parameters in previously totally healthy Covid-19 patients.