Virus and bateria
Virus and bacteria data were obtained from nasopharyngeal swabs (NPS) collected at enrolment. NPS were placed into skim milk tryptone glucose glycerol broth (STGGB), stored at -80°C. NPS bacterial pathogens were cultured at our institution22 and respiratory viruses using PCR undertaken at the Queensland Paediatric Infectious Diseases laboratory in Brisbane, as previously done19-21. For this study, we combined any bacteria detected as a single variable and only the two most frequently detected viruses (RSV and HRV) were analysed (so as to allow inclusion of more data). Further methods are detailed in the E-text file.