Study On Excess Mortality Of Seasonal Influenza In Shanghai From 2000 To 2006

Objective: To estimate the excess mortality of seasonal influenza in Shanghai, evaluate the impact of influenza epidemics, know about activity status and dynamic change of influenza, and provide scientific evidence for seasonal influenza vaccines usage. Detailed objective are as follows:To estimate excess mortality of seasonal influenza in past 7 seasons 2000-2006 in Shanghai using rate-difference model;To know about influenza activity status, dynamic change in Shanghai;To know about the severity of influenza epidemics in these cities, through comparing mortality estimates in different influenza seasons.Methods: Retrospectively during 2000-2006, Shanghai mortality data and influenza virus surveillance data were used to estimate excess mortality of influenze- associated 5 outcomes using rate difference models.Results: During 7 influenza season, excess mortality of AC in total population are 26.46 per million, 79.38 per million, 105.84 per million, 66.15 per million, 119.07 per million, 119.07 per million, 105.84 per million respectively. Annual excess mortality of 5 outcomes(PI, RC, AC, IHD, COPD) are 0.98 per million, 63.18 per million, 88.83 per million, 15.20 per million, 20.70 per million respectively. Annual excess mortality of 5 outcomes in≥65 group are 6-7 times higher than in total population, and the largest is excess mortality of AC,excess mortality of RC secondly. Excess mortality of AC in 0-4 group is higher than total population, but is lower than≥65 group.During 3 season of 2003/04, 2004/05 and 2006/07, H3N2 predominated. During 2 season of 2001/02 and 2002/03, influenza B predominated. During 2 season of 2000/01 and 2005/06, H1N1 predominated. During the 7 season, excess mortality of 5 outcomes presented a"M"shape when traced out by a line graph. Excess mortality reached a peak value in 2002/03 season, declined after that, then reached a bigger peak value in 2 season of 2004/05 and 2005/06, and declined again in 2006/07 season.Conclusion: Subtype of active-influenza changed frequently during the 7 influenza season, and leads to marked excess mortality. Seasons dominated by influenza A accounted for 70% of all the 7 season. During the 7 season, influenza posted the greatest threat to≥65 group. The study indicates that vaccinating≥65 group and chronic cardiovascular patients in time can reduce the risk of health damage to these people.