广东省2009年甲型H1N1流感大流行第一波人群感染状况分析

Sero-epidemiological survey on general community population to understand the infection status after the first wave of pandemic 2009 H1N1 influenza in Guangdong province

目的 了解2009年广东省甲型H1N1流感大流行第一波人群感染状况.方法 采取分层随机抽样方法,按照地区分层（大城市、中小城市和农村）和年龄组分层抽样,抽取调查对象4500人.大城市1500人样本选择在广州市,分布在5个区（每个区选择3个街道） 中等城市和农村各抽取1500人,分布在其他20个地市（每个地市抽取1个县,每个区/县至少抽取1个街道和镇,每个街道分别抽取1～2个居委会和村）.每个居委会或村按照随机抽样原则选取抽样对象.全部调查对象均未接种甲型H1N1流感疫苗.采用红细胞凝集抑制试验检测人群甲型H1N1流感血清抗体,抗体水平达到1∶40以上为阳性.结果 共调查4319人,调查对象分布在21个市25个县（区）85个街道（镇）144个居委会或村.抗体阳性985人,阳性率为22.82%.询问6月以来是否出现感冒症状,其中无任何症状的人群阳性率为23.47%（471/2007）,有其中一项发热、咳嗽、咽痛症状的人群阳性率为26.25%（714/2720）,流感样症状的人群阳性率为29.69%（337/1135）.结论 广东省甲型H1N1流感大流行第一波人群感染率达22.82%（985/4317）,估算自然感染人数为2178万人.

Objective To understand the infection status of pandemic 2009 H1N1 influenza after the first epidemic wave and to estimate the infected population. Methods Multi-stage stratified random sampling was introduced with 4500 subjects chosen in Guangdong province. 1500 people were selected from 5 districts （3 streets were selected in every district） in Guangzhou city which was representing the large cities. 1500 people were respectively selected from medium-sized city and rural areas, including 20 cities （1 county or district was selected in every city, at least 1 street or town was selected in every county or district respectively and then 1-2 residential area or county was selected in every street or township, respectively）. Every sample was selected in accordance with the principle of random sampling, excluding those who had injected with novel H1N1 vaccine. We used hemagglutination inhibition test to understand the serum antibody level of novel H1N1, with title of 1∶40 as positive. Results A number of 4319 specimens, distributed in 21 cities, 25 counties, 85 streets or townships, 144 residential areas, were tested, with an overall positive rate as 22.82% （985/4319）. The positive rate of those who had no symptoms of cold since June was 23.47% （471/2007）.The positive rate of those who had fever, cough or sore throat was 26.25% （714/2720）. The positive rate of those who had influenza-like illness （ILI） was 29.69% （337/1135 ）. Conclusion The infection rate in the first epidemic wave of the novel influenza A （H1N1） pandemic in Guangdong province was 22.82%（985/4317）. Based on the number of residonts in Guangdong province, the number of natural was estimated to have reached 21.78 million.