Human infections with avian influenza A(H7N9) virus in China: preliminary assessments of the age and sex distribution.

WPSAR Vol 4, No 2, 2013 | doi: 10.5365/wpsar.2013.4.2.005 www.wpro.who.int/wpsar 1 a Emerging Disease Surveillance and Response, Division of Health Security and Emergencies, World Health Organization Regional Offi ce for the Western Pacifi c, Manila, Philippines. b Emerging Disease Surveillance and Response, World Health Organization China Offi ce, Beijing, China. * Members of the World Health Organization Regional Offi ce for the Western Pacifi c Event Management Team: Nyka Alexander, Jang Hwan Bae, Joy Rivaca Caminade, Erica Dueger, Xavier Dufrenot, Norikazu Isoda, Frank Konings, Chin-Kei Lee, Ailan Li, Michelle McPherson, Satoko Otsu, Karl Schenkel and Huu Thuan Vo. Submitted: 13 April 2013; Published: 20 April 2013 doi: 10.5365/wpsar.2013.4.2.005 Since 31 March 2013, the Government of China has been notifying the World Health Organization (WHO) of human infections with the avian influenza A(H7N9) virus,1 as mandated by the International Health Regulations (2005).2 While human infections with other subgroups of H7 influenza viruses (e.g. H7N2, H7N3 and H7N7) have previously been reported,3 the current event in China is of historical significance as it is the first time that A(H7N9) viruses have been detected among humans and the first time that a low pathogenic avian influenza virus is being associated with human fatalities.4 In this rapidly evolving situation, detailed epidemiologic and clinical data from reported cases are limited—making assessments challenging— however, some key questions have arisen from the available data. Age and sex data, as one of the first and Human infections with avian infl uenza A(H7N9) virus in China: preliminary assessments of the age and sex distribution