| Background:Influenza is one of the most burdensome and vaccine-preventable diseases, which is characterized by rapid transmission, spreading to large areas and susceptible to all populations. The highest risk of serious outcomes and deaths occur among pregnant women, young children, elderly and individuals with certain chronic medical conditions. Therefore, influenza has always been a serious public health problem both in the world and in China. Estimation of influenza-associated excess mortality burden contributes to assess the severity of influenza epidemics and provide evidence-based on public health decision making. To estimate the national and provincial mortality burden related to influenza is necessary, for that it contributes to a deeper understanding of harmfulness of influenza for the government as well as the public, and also guide the development of intervention measures and the allocation of medical resources.Objective:To estimate influenza-associated excess mortality rates and excess deaths attributed to respiratory and circulatory diseases (R&C) on national-and provincial-level,2004-2005 to 2008-2009.Methods:Regional excess mortality associated with influenza from 2004-2005 through 2008-2009 was estimated as sample data by applying binominal negative regression model with mortality data and nationinfluenza virlogical data firstly. Then we estimated the national and provincial mortality burden associated with influenza by applying two indirect methods-Disease surveillance points stratification method and Per-capita gross domestic product method with sample data, mortality data, influenza virlogical data and per-capita gross domestic product data. As A(H1N1)pdm09 virus was the dominant strain circulating in China during the season 2009-2010, this article was mainly on excess mortality burden of epidemics from 2004-2005 through 2009-2010.Results:During the period 2004-2005 to 2008-2009, annual average numbers of influenza associated R&C excess deaths were 148602 and the corresponding excess mortality rate was 11.5 per 100000 population. The influenza associated mortality rate showed significant difference among annual epidemics, and it was highest in 2007-2008 and lowest in 2008-2009, the corresponding rate was 16.0 and 7.3 per 100 000 population. Most of deaths occurred in≥65 age-group and only 13.9% occurred in 0-64 age-group, the annual excess mortality rate was 126.3 and 1.7 per 100000 population. The influenza associated mortality rate showed significant difference also showed significant difference among provinces. The provincial excess mortality rate ranged from 8.6 to 15.0 per 100000 population, showing lower in southern provinces and the lowest in Guangdong, Guangxi and Yunnan. While the annual average numbers of excess deaths were highest in Jiangsu, Sichuan, Henan and Shandong (higher than 9000 person) and lowest in Tibet, Ningxia, Qinghai and Hainan (less than 1000 person). The annual average excess mortality rate of each province showed no significant difference bwteen rural and urban areas, because of different population size most of deaths occurred in rural areas except Beijing, Shanghai and Tianjin.Conclusion:During the period of 2004-2005 through 2008-2009, annual epidemics of influenza could cause severe excess mortality burden in China. And the excess mortality rate of seasonal epidemics showed significant provincial difference. The excess mortality burden of seasonal epidemics was higher in northern provinces especially in Beijing, Tianjin, Henan and Shandong during. Most of deaths occurred in≥65 age-group for all provinces. In conclusion, influenza viral surveillance should be further strengthened. The public, especially the high risk groups of influenza, should raise their awareness of harmfulness of influenza and understand intervention measures of influenza. And influenza vaccination should be implemented for the elderly every year to reduce the incidence of influenza infection and the risk of death. |
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