Can laboratory evaluation differentiate between coronavirus disease-2019, influenza, and respiratory syncytial virus infections? A retrospective cohort study

AIM: To identify clinical and laboratory parameters that can assist in the differential diagnosis of coronavirus disease 2019 (COVID-19), influenza, and respiratory syncytial virus (RSV) infections. METHODS: In this retrospective cohort study, we obtained basic demographics and laboratory data from all 685 hospitalized patients confirmed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza virus, or RSV from 2018 to 2020. A multiple logistic regression was employed to investigate the relationship between COVID-19 and laboratory parameters. RESULTS: SARS-CoV-2 patients were significantly younger than RSV (P = 0.001) and influenza virus (P = 0.022) patients. SARS-CoV-2 patients also displayed a significant male predominance over influenza virus patients (P = 0.047). They also had significantly lower white blood cell count (median 6.3 × 10(6) cells/μ) compared with influenza virus (P < 0.001) and RSV (P = 0.001) patients. Differences were also observed in other laboratory values but were insignificant in a multivariate analysis. CONCLUSIONS: Male sex, younger age, and low white blood cell count can assist in the diagnosis of COVID-19 over other viral infections. However, the differences between the groups were not substantial enough and would probably not suffice to distinguish between the viral illnesses in the emergency department.