Abstract
Background: We investigated the association between age, duration of clinical symptoms and viral shedding in outpatient children infected with respiratory syncytial virus (RSV) in Japan. Methods: Outpatients younger than 2 years of age, with suspected RSV infection between 2014 and 2018, were enrolled in the study. Following informed consent, nasal samples were collected at first and second clinic visits (with 0-9 days gap). RSV-A or -B infection and viral load were determined by real-time polymerase chain reaction. Clinical symptoms were recorded at first clinic visit, and fever and symptoms were recorded at home for up to 8 days. Association between clinical symptoms and patient characteristics, such as age, sex and birth weight, were analyzed using ordered logistic regression analysis. The association between viral reduction and estimated shedding period was examined using linear regression analysis. Results: Among the 205 cases enrolled in the study, no difference was found in patient characteristics between RSV-A and -B infection. Duration of fever was prolonged with increased age. Duration of rhinorrhea and cough was shorter in females than in males and in groups with birth weight ≥3 kg than in those with <2.5 kg. Daily viral reduction increased and estimated viral elimination period decreased with age. Conclusions: Fever duration was found to increase while viral shedding decreased with patient age.