The purpose of this study is to collect clinical outcome and nasal viral load information.

There is no vaccine available to prevent Respiratory Syncytial Virus disease; however, a humanized monoclonal antibody is approved for the prevention of Respiratory Syncytial Virus infection in pediatric patients at high risk of disease (eg, pre-term infants, congenital heart disease, and chronic lung disease). Beyond this high-risk group, infection is common in otherwise healthy infants and can be severe, leading to hospitalization and while uncommon, death. Each year in the United States, approximately 100,000 Respiratory Syncytial Virus-related hospitalizations occur in low risk infants. Currently, treatment of infants suffering from Respiratory Syncytial Virus disease is limited to supportive care with the goal of maintaining adequate oxygenation and nutrition.

The availability of a novel anti-Respiratory Syncytial Virus therapeutic that reduces the number of hospitalizations related to Respiratory Syncytial Virus infection would fulfill an unmet medical need in the pediatric population. For maximum effect, such a treatment should be administered as early as possible in the course of infection. Accordingly, the opportunities for early intervention with an anti-Respiratory Syncytial Virus therapeutic are in the outpatient setting, prior to hospitalization. However, the incidence of Respiratory Syncytial Virus-related hospitalization, as well as the natural history and viral dynamics of Respiratory Syncytial Virus infection, remain undefined in the outpatient setting. A better understanding of the prevalence of Respiratory Syncytial Virus infection and subsequent hospitalization rates among symptomatic infants as well as the early disease course of Respiratory Syncytial Virus infection will help in the design of clinical trials needed to assess the efficacy of an anti-Respiratory Syncytial Virus therapeutic developed by Gilead Sciences.

Inclusion Criteria:

• < 24 months of age
• ≥ 35 weeks gestational age at birth
• Signs of acute Respiratory Tract Infection < 5 days
• Ability to contact parent or legal guardian for follow up

Exclusion Criteria:

• Ongoing Respiratory Tract Infection
• Lung disease
• Heart disease
• Respiratory Syncytial Virus medication in the last 6 months
• Participation in a study with investigational medicinal product in the last 28 days

Outpatient pediatric clinics, urgent care facilities or emergency departments