Specimen collection, storage, laboratory testing
All respiratory specimens (including participant-collected and nurse-collected swabs) were transported to refrigerators at sub-district health centers within 24 hours of collection, kept between 2 – 8 °C before being frozen in liquid nitrogen tanks below -70 °C, and sent weekly to the Thai National Institute of Health (NIH) in Nonthaburi. Respiratory specimens were tested for influenza viruses and RSV with real-time reverse-transcription polymerase chain reaction test (rRT-PCR) according to CDC/WHO protocols [15, 16].