Estimating Influenza-associated Mortality in Korea: The 2009-2016 Seasons

Objectives Estimating influenza-associated mortality is important since seasonal influenza affects persons of all ages, causing severe illness or death. This study aimed to estimate influenza-associated mortality, considering both periodic changes and age-specific mortality by influenza subtypes. Methods Using the Microdata Integrated Service from Statistics Korea, we collected weekly mortality data including cause of death. Laboratory surveillance data of respiratory viruses from 2009 to 2016 were obtained from the Korea Centers for Disease Control and Prevention. After adjusting for the annual age-specific population size, we used a negative binomial regression model by age group and influenza subtype. Results Overall, 1 859 890 deaths were observed and the average rate of influenza virus positivity was 14.7% (standard deviation [SD], 5.8), with the following subtype distribution: A(H1N1), 5.0% (SD, 5.8); A(H3N2), 4.4% (SD, 3.4); and B, 5.3% (SD, 3.7). As a result, among individuals under 65 years old, 6774 (0.51%) all-cause deaths, 2521 (3.05%) respiratory or circulatory deaths, and 1048 (18.23%) influenza or pneumonia deaths were estimated. Among those 65 years of age or older, 30 414 (2.27%) all-cause deaths, 16 411 (3.42%) respiratory or circulatory deaths, and 4906 (6.87%) influenza or pneumonia deaths were estimated. Influenza A(H3N2) virus was the major contributor to influenza-associated all-cause and respiratory or circulatory deaths in both age groups. However, influenza A(H1N1) virus–associated influenza or pneumonia deaths were more common in those under 65 years old. Conclusions Influenza-associated mortality was substantial during this period, especially in the elderly. By subtype, influenza A(H3N2) virus made the largest contribution to influenza-associated mortality.

[1]  B. Jiang,et al.  Effects and interaction of meteorological factors on influenza: Based on the surveillance data in Shaoyang, China. , 2019, Environmental research.

[2]  K. Pantavou,et al.  Mortality attributable to seasonal influenza in Greece, 2013 to 2017: variation by type/subtype and age, and a possible harvesting effect , 2019, Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin.

[3]  J. Mossong,et al.  European all-cause excess and influenza-attributable mortality in the 2017/18 season: should the burden of influenza B be reconsidered? , 2019, Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases.

[4]  K. Mølbak,et al.  Influenza‐associated mortality determined from all‐cause mortality, Denmark 2010/11‐2016/17: The FluMOMO model , 2018, Influenza and other respiratory viruses.

[5]  A. Fauci,et al.  Chasing Seasonal Influenza - The Need for a Universal Influenza Vaccine. , 2018, The New England journal of medicine.

[6]  A. Fowlkes,et al.  Estimated rates of influenza‐associated outpatient visits during 2001‐2010 in 6 US integrated healthcare delivery organizations , 2018, Influenza and other respiratory viruses.

[7]  Xiling Wang,et al.  Excess pneumonia and influenza mortality attributable to seasonal influenza in subtropical Shanghai, China , 2017, BMC Infectious Diseases.

[8]  Peng Wu,et al.  Influenza‐associated mortality in Yancheng, China, 2011‐15 , 2017, Influenza and other respiratory viruses.

[9]  Richard A. White,et al.  Excess all-cause and influenza-attributable mortality in Europe, December 2016 to February 2017 , 2017, Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin.

[10]  Kazuhiko Ito,et al.  Seasonal Influenza Infections and Cardiovascular Disease Mortality. , 2016, JAMA cardiology.

[11]  Peng Wu,et al.  Influenza-Associated Excess Mortality in South Korea. , 2016, American journal of preventive medicine.

[12]  Jianyun Lu,et al.  Influenza associated mortality in Southern China, 2010-2012. , 2014, Vaccine.

[13]  A. Noymer,et al.  Influenza Mortality in the United States, 2009 Pandemic: Burden, Timing and Age Distribution , 2013, PloS one.

[14]  W. Thompson,et al.  Time-series analyses of count data to estimate the burden of seasonal infectious diseases. , 2012, Epidemiology.

[15]  M. Kretzschmar,et al.  Mortality attributable to 9 common infections: significant effect of influenza A, respiratory syncytial virus, influenza B, norovirus, and parainfluenza in elderly persons. , 2012, The Journal of infectious diseases.

[16]  Hong Zhou,et al.  Hospitalizations associated with influenza and respiratory syncytial virus in the United States, 1993-2008. , 2012, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America.

[17]  Weizhong Yang,et al.  Influenza-associated mortality in temperate and subtropical Chinese cities, 2003-2008. , 2012, Bulletin of the World Health Organization.

[18]  R. Pebody,et al.  Mortality caused by influenza and respiratory syncytial virus by age group in England and Wales 1999–2010 , 2012, Influenza and other respiratory viruses.

[19]  Harish Nair,et al.  Global burden of respiratory infections due to seasonal influenza in young children: a systematic review and meta-analysis , 2011, The Lancet.

[20]  Cecile Viboud,et al.  Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004 , 2011, PloS one.

[21]  Influenza, Seasonal , 2011, My Child Is Sick!, 2nd Ed.

[22]  C. Bridges,et al.  Estimating influenza-associated deaths in the United States. , 2009, American journal of public health.

[23]  L. Brammer,et al.  Influenza circulation and the burden of invasive pneumococcal pneumonia during a non-pandemic period in the United States. , 2010, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America.

[24]  Lynnette Brammer,et al.  Estimates of US influenza‐associated deaths made using four different methods , 2009, Influenza and other respiratory viruses.

[25]  C. Bridges,et al.  The annual impact of seasonal influenza in the US: measuring disease burden and costs. , 2007, Vaccine.

[26]  C. Bridges,et al.  Influenza- and RSV-associated hospitalizations among adults. , 2007, Vaccine.

[27]  W. Thompson,et al.  Epidemiology of seasonal influenza: use of surveillance data and statistical models to estimate the burden of disease. , 2006, The Journal of infectious diseases.

[28]  Angela Chow,et al.  Influenza-associated Deaths in Tropical Singapore , 2006, Emerging infectious diseases.

[29]  Keiji Fukuda,et al.  Influenza-associated hospitalizations in the United States. , 2004, JAMA.

[30]  T. Lieu,et al.  Incidence of outpatient visits and hospitalizations related to influenza in infants and young children. , 2004, Pediatrics.

[31]  Keiji Fukuda,et al.  Mortality associated with influenza and respiratory syncytial virus in the United States. , 2003, JAMA.

[32]  W. Thompson,et al.  Observations on mortality during the 1918 influenza pandemic. , 2001, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America.

[33]  R. Davis,et al.  Influenza and the rates of hospitalization for respiratory disease among infants and young children. , 2000, The New England journal of medicine.

[34]  R. Serfling,et al.  Observations on excess mortality associated with epidemic influenza. , 1961, Maryland state medical journal.

[35]  R. Evans.  European Centre for Disease Prevention and Control. , 2014, Nursing standard (Royal College of Nursing (Great Britain) : 1987).