In the IRIS, NTSs were collected by a trained HCP on days 1 and 6 after recruitment in the outpatient clinic and self-collected by subjects at home on day 3 after receiving detailed instruction on swab technique from the HCP at baseline. During the clinic visits, the nasal swab was collected by inserting and rotating a separate flocked sterile swab (Copan) through each nostril into the posterior nares, and throat swabs were collected by swabbing a sterile flocked swab on both the tonsillar fossae and posterior pharynx. The flocked end of the 2 nasal swabs and the throat swab were then transferred to a vial containing Copan Universal Transport Medium by breaking the prescored breaking point of the plastic swab shaft. Specimens collected in the clinic on day 1 and day 6 were stored directly in a clinic refrigerator at 4°C-8°C after collection.