Nanjing Medical University, Nanjing Medical University - School of Public Health, Government of the United States of America - Centers for Disease Control and Prevention (CDC), affiliation not provided to SSRN, World Health Organization (WHO) - Department of Immunization, Vaccines and Biologicals (IVB), Boston University - Department of Global Health, Chris Hani Baragwanath Academic Hospital - Vaccines and Infectious Diseases Analytics Research Unit, Yale University - Institute for Global Health, University of Colorado at Denver - Department of Pediatrics, University of Edinburgh - College of Medicine & Veterinary Medicine, affiliation not provided to SSRN, National Center for Communicable Diseases, University of Barcelona - Institut de Salut Global de Barcelona (ISGlobal), Hospices Civils de Lyon - Laboratoire de Virologie, NCDC, Murdoch Children's Research Institute - Infection and Immunity, Smorodintsev Research Institute of Influenza, Murdoch Children's Research Institute - Infection and Immunity, affiliation not provided to SSRN, Hospital de Niños R. Gutiérrez, University of Michigan at Ann Arbor - Department of Epidemiology, University of Turku - Department of Pediatrics, National Centre for Biosecurity and Infectious Disease (NCBID) - Institute of Environmental Science and Research Limited (ESR), affiliation not provided to SSRN, All India Institute of Medical Sciences, New Delhi, affiliation not provided to SSRN, University of Split, affiliation not provided to SSRN, Perth Children’s Hospital - Telethon Kids Institute, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), affiliation not provided to SSRN, Tehran University of Medical Sciences, MAHAN Trust Mahatma Gandhi Tribal Hospital, affiliation not provided to SSRN, Hospital de Santa Maria, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, affiliation not provided to SSRN, Nagasaki University - Department of Pediatric Infectious Diseases, Nanyang Technological University (NTU) - Lee Kong Chian School of Medicine, University of Cape Town (UCT) - Department of Pediatrics and Child Health, affiliation not provided to SSRN, University of Edinburgh - College of Medicine & Veterinary Medicine and affiliation not provided to SSRN

National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, Government of the United States of America - Division of Influenza, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - National Institute for Communicable Diseases, National Health Laboratory Services (NHLS) - National Institute for Communicable Diseases, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - National Institute for Communicable Diseases, Centers for Disease Control and Prevention (CDC) - Influenza Division, Genesis Analytics, Genesis Analytics, Genesis Analytics, Genesis Analytics, Genesis Analytics, University of the Witwatersrand, Epicentre Health Research, University of the Witwatersrand - Perinatal HIV Research Unit, University of the Witwatersrand - Perinatal HIV Research Unit, National Health Laboratory Services (NHLS) - National Institute for Communicable Diseases, Ampath Pathology and National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis

National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, Centers for Disease Control and Prevention (CDC) - Influenza Division, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, University of the Witwatersrand - Perinatal HIV Research Unit, University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit, University of the Witwatersrand - Perinatal HIV Research Unit, Chris Hani Baragwanath Academic Hospital - Perinatal HIV Research Unit, University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit, University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, South African Medical Research Council - Health Systems Research Unit, North-West University - Unit for Environmental Sciences and Management, North-West University - Unit for Environmental Sciences and Management, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, Government of the United States of America - Division of Influenza and Independent