Rapid screening of COVID‐19 patients using white blood cell scattergrams, a study on 381 patients

Summary Complementary tools are warranted to increase the sensitivity of the initial testing for COVID‐19. We identified a specific ‘sandglass’ aspect on the white blood cell scattergram of COVID‐19 patients reflecting the presence of circulating plasmacytoid lymphocytes. Patients were dichotomized as COVID‐19‐positive or ‐negative based on reverse transcriptase polymerase chain reaction (RT‐PCR) and chest computed tomography (CT) scan results. Sensitivity and specificity of the ‘sandglass’ aspect were 85·9% and 83·5% respectively. The positive predictive value was 94·3%. Our findings provide a non‐invasive and simple tool to quickly categorize symptomatic patients as either COVID‐19‐probable or ‐improbable especially when RT‐PCR and/or chest CT are not rapidly available.