Section Tropical Medicine, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
Euro Surveill. 2012 Jan 12;17(2):20052.
The 2009 influenza pandemic has introduced the new re-assorted influenza A(H1N1)pdm09 virus which recirculated during the 2010/11 influenza season. Before that season, it was possible to acquire protective immunity either by pandemic or seasonal influenza vaccination against influenza A(H1N1)pdm09 or by natural infection. To obtain data on vaccination coverage and antibody levels in a reference population and to calculate whether or not the herd immunity threshold (HIT, calculated as 33% given an R0 of 1.5) was reached at the beginning of the 2010/11 season we performed a seroprevalence study in November 2010 in Hamburg, Germany. Antibody titres were assessed applying a haemagglutination inhibition test. Vaccination coverage was very low: 14% for pandemic and 11% for seasonal 2010/11 vaccinations. Even in those with underlying risk factors, vaccination coverage was not much higher: 17% for both vaccines. Serological analysis revealed antibody titres of ≥1:10 in 135 of 352 (38%) and of ≥1:40 in 61 of 352 study participants (17%). Specific antibodies were measurable in 26% of those without history of vaccination or natural infection, indicating a high proportion of subclinical and mild influenza disease. Nevertheless, the HIT was not reached, leaving the majority of the population susceptible to influenza A(H1N1)pdm09 and its potential complications.
2009 年流感大流行引入了新的重配甲型 H1N1pdm09 流感病毒，该病毒在 2010/11 流感季节中再次循环。在此之前，人们可以通过接种大流行或季节性流感疫苗来获得针对甲型 H1N1pdm09 的保护性免疫，或者通过自然感染来获得这种免疫。为了获得参考人群中疫苗接种覆盖率和抗体水平的数据，并计算在 2010/11 季节开始时是否达到了群体免疫阈值（HIT，在 R0 为 1.5 的情况下计算为 33%），我们在 2010 年 11 月在德国汉堡进行了血清流行率研究。应用血凝抑制试验评估抗体滴度。疫苗接种覆盖率非常低：大流行疫苗接种率为 14%，2010/11 季节性疫苗接种率为 11%。即使在有潜在风险因素的人群中，疫苗接种覆盖率也没有高很多：两种疫苗的接种率均为 17%。血清学分析显示，在 352 名研究参与者中的 135 名（38%）中抗体滴度≥1:10，在 61 名（17%）中抗体滴度≥1:40。在没有接种疫苗或自然感染史的人群中，有 26%的人可检测到特异性抗体，表明存在大量亚临床和轻度流感疾病。然而，HIT 并未达到，使大多数人易感染甲型 H1N1pdm09 及其潜在并发症。
