- Exposure: the presence of another family member in the household who is ill with a URI, or a child in the family that is attending preschool, or attending school with ≥6 children in the class; c.Except for allergic rhinitis or a URI, children/adolescents are in normal physical health (i.e., no clinically significant systemic disease) as judged by the Investigator upon physical examination of the subject; d.Subjects do not require concomitant medication except for low-dose inhaled glucocorticoids for allergic rhinitis or mild concomitant asthma, if dose is stabilized before entry in the study (i.e., dose is not changed for one month prior to or during the study), and inhaled short-acting beta-2 adrenergic agonists for concomitant asthma, as needed; e.Post menarchal females must be using a reliable method of contraception (i.e., oral, transdermal, injectable or implanted contraceptives, IUD, cervical cap, diaphragm, condom, abstinence, or surgical sterility); f.Parent/guardian/adolescent provides written informed consent and child provides assent, if age appropriate.