• 作者：Lorena Simó ; n Mé ; ndez^a ; ^{lorenas@isciii.es} ; Salvador de Mateo Ontañ ; ó ; n^a ; ^b ; Amparo Larrauri Cá ; mara^a ; ^b ; Silvia Jimé ; nez-Jorge^a ; ^b ; Josep Vaqué ; Rafart^c ; Santiago Pé ; rez Hoyos^d ; en representació ; n del Sistema de Vigilancia de Gripe en Españ ; a (SVGE)^&loz ;
• 关键词：Pandemia de gripe ; Virus de la gripe A(H1N1)2009 ; Nú ; mero de reproducció ; n ; Indicadores de mortalidad
• 刊名：Gaceta Sanitaria
• 出版年：2011
• 期刊代码：pca166_02139111
• 类别：med
• 出版时间：July-August 2011
• 卷：25
• 期：4
• 页码：296-302
• 文件大小：224 K

Objectives

To estimate the value of the basic reproduction number for the pandemic wave of influenza A (H1N1) 2009 in Spain and to assess its impact on morbidity and mortality in the Spanish population compared with those in the previous influenza season.

Methods

Data on the incidence of influenza and viral detections were obtained from the Spanish Influenza Surveillance System. Deaths from pandemic influenza were obtained from the Coordinating Center for Health Alerts and Emergencies of the Spanish Ministry of Health and Social Policy, and deaths from seasonal influenza during the period 2003-2008 were obtained from the National Statistics Institute. The reproduction number was estimated by two methods: firstly, by using the growth rate of the cumulative incidence of influenza during the exponential growth phase of the pandemic wave, and secondly (maximum likelihood estimation), through analysis the dates of onset of symptoms observed in pairs of cases based on generation time distribution. We calculated the fatality rate and mortality from influenza by comparing potential years of life lost in the pandemic season with those in previous interpandemic seasons.

Results

The start of the pandemic wave occurred in Spain earlier in week 40/2009 (from 4 to 10 October), with an absolute predominance of the new strain in the pattern of circulating viruses. The value of R₀ in the growth phase of the wave was 1.29 (95%CI: 1.25-1.33), estimated with the first method, and was 1.01 (95%CI: 0.99-1.03) with the second method. During the pandemic season, there were 318 deaths from pandemic influenza, affecting younger age groups than in previous interpandemic seasons. Consequently, the number of potential years of life lost in the pandemic season (11,612) was estimated at six times the adjusted annual average of the interpandemic influenza seasons for comparison (1,802).

Conclusions

The estimates of R₀ for the growth phase of the pandemic wave were in the lower range of estimates of this parameter in previous pandemics. Mortality indicators calculated in the pandemic period showed an increase in deaths compared with previous interpandemic seasons, which was most pronounced in young patients.