Sample collection and testing. A deep nasal swab, obtained by a small flexible nylon flocked swab (Copan Diagnostics, Corona, CA) inserted approximately one half the distance between the nares and bridge of the nose, was used for all sample collections. After collecting the specimen, the swab was rinsed vigorously in 0.5 mL of lysis buffer. Samples were stored at room temperature until testing (12) . Total nucleic acid was extracted from 200 L of swab specimen in lysis buffer as described previously (13) . One thousand copies/reaction of an external control was added to identify false-negative PCR results (14) . Nasal swab samples were tested by quantitative PCR for respiratory syncytial virus A and B, human metapneumovirus (hMPV), influenza A and B, parainfluenza types 1, 2, 3, and 4, adenovirus, rhinovirus, and coronavirus (subtypes 229E, HKU1, NL63, and OC43) (7, (13) (14) (15) (16) .