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目的了解甲型H1N1流感病毒病原学变迁与变异特征,分析重症病例危险因素,为科学防控提供依据。方法建立甲型H1N1流感监测体系,定期收集生物学标本实施甲型H1N1流感病毒核酸检测、病毒分离与测序分析;利用Logistics回归模型分析重症病例发生死亡的危险因素。结果 2009-2013年甲型H1N1流感病毒分离阳性率分别为13.83%(481/3 479)、4.46%(136/3 047)、9.13%(233/2 550)、0(0/2 643)和4.68%(159/3 400)。共完成18株毒株测序,2009-2010年的9株毒株位于第一主干枝,2011年的4株甲型H1N1流感病毒毒株聚集成第二主干枝,2013年的5株毒株中有4株位于第三主干枝。从2011年起,甲型H1N1流感毒株与疫苗株相距较远;共报告重症病例77例,其中40例(57.14%)有基础疾患,死亡16例。多因素Logistic分析显示慢性肺部疾病进入回归方程,OR=7.72(95%CI:1.97~30.23)。结论甲型H1N1流感监测系统在广州运行良好。甲型H1N1流感已经取代了A(H1N1)流感呈现季节性流行,慢性肺部基础疾患是甲型H1N1流感重症病例发生死亡的危险因素。2011年起,甲流疫苗与广州人群的流行毒株匹配较差,应持续开展甲流监测,密切关注毒株变化特征。
Objective To understand the etiology and variation of influenza A (H1N1) virus, analyze the risk factors of severe cases, and provide the basis for scientific prevention and control. Methods The surveillance system of Influenza A (H1N1) was established. The biological specimens were collected regularly to detect the nucleic acid of Influenza A (H1N1) virus, the virus was isolated and sequenced. The risk factors of death in severe cases were analyzed by Logistics regression model. Results The positive rates of influenza A (H1N1) virus isolates in 2009-2013 were 13.83% (481/3 479), 4.46% (136/3 047), 9.13% (233/2 550), 0 (0/2 643) and 4.68% (159/3 400). A total of 18 strains were sequenced. Nine strains were located in the first trunk branch in 2009-2010. Four strains of H1N1 influenza virus were clustered into the second trunk branch in 2011. Among the five strains in 2013 4 are located in the third trunk branch. Since 2011, influenza A (H1N1) strains were far away from the vaccine strain. A total of 77 severe cases were reported, of which 40 (57.14%) had underlying diseases and 16 died. Multivariate logistic analysis showed that chronic lung disease entered the regression equation, OR = 7.72 (95% CI: 1.97-30.23). Conclusion Influenza A H1N1 Influenza Surveillance System works well in Guangzhou. Influenza A (H1N1) has replaced seasonal influenza A (H1N1), and chronic lung disease is a risk factor for death in severe cases of influenza A (H1N1). Since 2011, H1N1 vaccines have not matched the epidemic strains of Guangzhou people. A-flow monitoring should be continued to pay close attention to the characteristics of the virus strains.