Lu Li, Liu Dong-lei, Zhang Tie-gang, Chen Meng, Zhang Zhu-jiazi, Wang Xiao-li, Yang Zhen, Pang Xing-huo, Deng Ying
Department of Immunization and Prevention, Beijing Center for Disease Prevention and Control, Beijing 100013, China.
Zhonghua Jie He He Hu Xi Za Zhi. 2010 Jun;33(6):403-5.
To explore the herd immunity against influenza A (H1N1) in pre-vaccinated residents aged over 5 years, and therefore to provide data for vaccination policies in high risk populations.
From October to December 2009, Beijing CDC conducted a serum survey of the novel influenza A (H1N1) in the local residents, stratified in 10 age groups between 5 years to over 60 years, without H1N1 vaccination history and disease history. Hemagglutination inhibition (HI) assays were performed at Beijing CDC. Statistical significance was determined with geometric mean titer (GMT).
3499 serum samples were tested for HI antibody. The average level of HI antibody was 1:8.03, and 11.06% (387/3499) were sero-positive (HI antibody level ≥ 1:40). In the group aged from 5 to 19 years, the level of HI antibody and the sero-positive rate were higher (HI antibody > 1:8.9, sero-positive rate > 12%).
The antibody levels in different groups were affected by age specific morbidity, and the higher antibody level of the school-age group was correlated with higher disease intensity in this population. The data showed that the herd immunity in Beijing was under the optimal level, but influenza A (H1N1) would probably become prevalent in the short coming future.
探索5岁以上已接种疫苗居民对甲型H1N1流感的群体免疫力，从而为高危人群的疫苗接种政策提供数据。
2009年10月至12月，北京市疾病预防控制中心对当地居民进行了甲型H1N1流感血清学调查，将其分为5岁至60岁以上的10个年龄组，这些居民无甲型H1N1流感疫苗接种史和疾病史。北京市疾病预防控制中心进行了血凝抑制（HI）试验。采用几何平均滴度（GMT）确定统计学意义。
对3499份血清样本进行了HI抗体检测。HI抗体平均水平为1:8.03，血清阳性率为11.06%（387/3499）（HI抗体水平≥1:40）。在5至19岁年龄组中，HI抗体水平和血清阳性率较高（HI抗体>1:8.9，血清阳性率>12%）。
不同组的抗体水平受年龄特异性发病率影响，学龄组较高的抗体水平与该人群较高的疾病强度相关。数据显示，北京的群体免疫力处于最佳水平以下，但甲型H1N1流感可能在不久的将来流行。
