Background
Sepsis, SIRS, infections, infection, sepsis
SEPSIS, CORONAVIRUS DISEASE 2019, INFECTIONS, INFECTION, SYSTEMIC INFLAMMATORY RESPONSE SYNDROME, CORONAVIRUS, SEPSIS, SEVERE ACUTE RESPIRATORY SYNDROME
Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and cases of COVID-19 have been reported globally. The World Health Organization (WHO) declared a pandemic in March 2020. In Japan, it is widely known as an unprecedented infection in the twenty-first century. For example, the government issued a declaration of emergency depending on the increase in the number of infected people and the degree of strain on medical institutions.In the prevention, testing, and treatment of COVID-19, more effective, safer, and convenient methods are desired. Pathogenic genetic testing by polymerase chain reaction (PCR) was performed to confirm the presence or absence of SARS-CoV-2. Pathogenic genetic testing for COVID-19 can detect viruses with high sensitivity; however, there are several challenges. For example, dedicated analytical equipment and skilled human resources are needed, it takes several tens of minutes to several hours to obtain results, and the reagent cost per test is relatively high.In recent years, remarkable progress has been made in automated hematology analyzers for laboratory testing, and recent hematology analyzers can be used to analyze not only complete blood count (CBC) (including red blood cell (RBC) count, white blood cell (WBC) count, and platelet count parameters) and WBC differentiation, but also detailed information on WBC. WBC analysis was performed using an automated hematology analyzer, UniCel DxH 900 Series Coulter Cellular Analysis System (Beckman Coulter, K.K.; DxH 900), cell volume and internal cell structure were analyzed based on detecting and measuring changes in electrical resistance and scattered laser light of flow cytometry and conductivity of cells. These parameters are also utilized as numerical values. Since WBC analysis by an automated hematology analyzer can be performed in approximately one minute, clinical laboratories use this analysis as a daily routine examination in hematology testing. Monocyte distribution width (MDW) is a unique parameter of DxH 900 showing monocyte volume distribution width. In the US, DxH 900, which measures MDW as an Early Sepsis Indicator, has been approved by the United States (US) Food and Drug Administration (FDA) as a device to assess risk for sepsis. In Europe, DxH 900 has received a Conformité Européenne (CE) mark. MDW has been attracting attention as a new biomarker. There are reports indicating that MDWs are useful for the early diagnosis of sepsis in the emergency department and for differentiating systemic inflammatory response syndrome (SIRS) and sepsis [In severe infections such as sepsis, cytokine storms and activation of WBCs are known to occur [In this study, to explore the possibility of MDW as an infection biomarker in COVID-19 testing, we analyzed MDW in the COVID-19 group by severity, including mild, moderate I, and moderate II [