All NPA specimens were subjected to a panel of realtime reverse transcription-PCR (rRT-PCR) assays for the following viruses: infl uenza A (separate primer/probe sets for infl uenza A [universal], pandemic [H1N1] 2009, seasonal subtype H1N1, and seasonal subtype H3N1 detection) (20) ; infl uenza B (CDC in-house assay [details available on request]); respiratory syncytial virus (RSV; CDC in-house assay [details available on request]); and human metapneumovirus (HMPV) (21) . An internal control PCR specifi c for the human RNAseP gene was used to monitor sample adequacy and to detect the presence of PCR inhibitors (22) . Positive and negative controls were included in each PCR run. A Rotorgene 6000 real-time PCR thermocycler (Corbett Life Science, Mortlake, New South Wales, Australia) and SuperScript III One-Step RT-PCR Kits (Invitrogen, Carlsbad, CA, USA) were used throughout. All laboratory work was conducted at the Shoklo Malaria Research Unit microbiology laboratory in Mae Sot, Tak Province, Thailand.