A Comparison of the Epidemiological Characteristics Between Influenza and COVID-19 Patients: A Retrospective, Observational Cohort Study

• Published in: Curēus (Palo Alto, CA) Vol. 15; no. 11; p. e49280
• Main Authors: Naji, Omar, Darwish, Iman, Bessame, Khaoula, Vaghela, Tejal, Hawkins, Anja, Elsakka, Mohamed, Merai, Hema, Lowe, Jeremy, Schechter, Miriam, Moses, Samuel, Busby, Amanda, Sullivan, Keith, Wellsted, David, Zamir, Muhammad A, Kandil, Hala
• Format: Journal Article
• Language: English
• Published: United States Cureus Inc 23-11-2023
• Subjects: Coronaviruses; COVID-19; Epidemiology; Influenza; Lung diseases; United Kingdom > UK; Australia; covid-19; sars-cov-2 (severe acute respiratory syndrome coronavirus -2); chest radiograph; seasonal influenza; clinical epidemiology
• ISSN: 2168-8184; 2168-8184
• DOI: 10.7759/cureus.49280

Background and objective It is crucial to make early differentiation between coronavirus disease 2019 (COVID-19) and seasonal influenza infections at the time of a patient's presentation to the emergency department (ED). In light of this, this study aimed to identify key epidemiological, initial laboratory, and radiological differences that would enable early recognition during co-circulation. Methods This was a retrospective, observational cohort study. All adult patients presenting to our ED at the Watford General Hospital, UK, with a laboratory-confirmed diagnosis of COVID-19 (2019/20) or influenza (2018/19) infection were included in this study. Demographic, laboratory, and radiological data were collected. Binary logistic regression was employed to determine features associated with COVID-19 infection rather than influenza. Results Chest radiographs suggestive of viral pneumonitis and older age (≥80 years) were associated with increased odds of having COVID-19 [odds ratio (OR): 47.00, 95% confidence interval (CI): 21.63-102.13 and OR: 64.85, 95% CI: 19.96-210.69 respectively]. Low eosinophils (<0.02 x 10
/L) were found to increase the odds of COVID-19 (OR: 2.12, 95% CI: 1.44-3.10, p<0.001). Conclusions Gaining awareness about the epidemiological, biological, and radiologic presentation of influenza-like illness can be useful for clinicians in ED to differentiate between COVID-19 and influenza. This study showed that older age, eosinopenia, and radiographic evidence of viral pneumonitis significantly increase the odds of having COVID-19 compared to influenza. Further research is needed to determine if these findings are affected by acquired or natural immunity.