Epidemiological Characteristics and Outcomes of COVID-19 in Asymptomatic Versus Symptomatic Patients

Background: The clinical manifestations of COVID-19 are different, which can be attributed to asymptomatic carriers, acute respiratory disease and pneumonia with different severities. The aim of this study was to compare the epidemiological characteristics and outcomes of COVID-19 in patients with clinical symptoms versus asymptomatic patients.

Methods: In this retrospective cohort study, the epidemiological characteristics of two groups of patients, with clinical symptoms (n = 38,630) and without clinical symptoms who were definitive cases of COVID-19 (n = 2,327) were investigated in the southwestern of Iran. Chi-square test was used to evaluate the differences between qualitative variables in the two study groups.

Results: Of 40,957 patients with COVID-19, 2,327 (5.68%) were asymptomatic, of whom 1391 (59.77%) were males, 1841 patients (79.11%) had a history of contact with definite or suspected cases of COVID-19. Asymptomatic patients were older than symptomatic cases. Patients with clinical symptoms had higher mortality rate than asymptomatic patients (2.68% in symptomatic patients vs 0% in asymptomatic patients).

Conclusion: According to the results of our study, the detected viral load in asymptomatic individuals was similar to that of symptomatic patients, indicating that asymptomatic infections can potentially transmit the disease. Therefore, screening and detection of asymptomatic cases is an important and key measure in prevention and early control of COVID-19 worldwide.