Division of Infectious Disease Control, Norwegian Institute of Public Health, Oslo, Norway.
BMC Infect Dis. 2012 Mar 20;12:63. doi: 10.1186/1471-2334-12-63.
During the 2009-2010 pandemic in Norway, 12 513 laboratory-confirmed cases of pandemic influenza A(H1N1)pdm09, were reported to the Norwegian Surveillance System for Communicable Diseases (MSIS). 2.2 million persons (45% of the population) were vaccinated with an AS03-adjuvanted monovalent vaccine during the pandemic. Most of them were registered in the Norwegian Immunisation Registry (SYSVAK). Based on these registries, we aimed at estimating the vaccine effectiveness (VE) and describing vaccine failures during the pandemic in Norway, in order to evaluate the role of the vaccine as a preventive measure during the pandemic.
We conducted a population-based retrospective cohort study, linking MSIS and SYSVAK with pandemic influenza vaccination as exposure and laboratory-confirmed pandemic influenza as outcome. We measured VE by week and defined two thresholds for immunity; eight and 15 days after vaccination.
The weekly VE ranged from 77% to 96% when considering 15 days or more after vaccination as the threshold of immunity and from 73% to 94% when considering eight days or more. Overall, 157 individuals contracted pandemic influenza eight or more days after vaccination (8.4/100,000 vaccinated), of these 58 had onset 15 days or more after vaccination (3.0/100,000 vaccinated). Most of the vaccine failures occurred during the first weeks of the vaccination campaign. More than 30% of the vaccine failures were found in people below 10 years of age.
Having available health registries with data regarding cases of specific disease and vaccination makes it feasible to estimate VE in a simple and rapid way. VE was high regardless the immunity threshold chosen. We encourage public health authorities in other countries to set up such registries. It is also important to consider including information on underlying diseases in registries already existing, in order to make it feasible to conduct more complete VE estimations.
在 2009 年至 2010 年挪威大流行期间，向挪威传染病监测系统 (MSIS) 报告了 12513 例经实验室确认的大流行性流感 A(H1N1)pdm09 病例。在大流行期间，有 220 万人（占人口的 45%）接种了一种含佐剂的单价疫苗。他们中的大多数人都在挪威免疫登记处 (SYSVAK) 登记。基于这些登记处，我们旨在估计大流行期间疫苗的有效性 (VE) 并描述疫苗失败情况，以评估疫苗在大流行期间作为预防措施的作用。
我们进行了一项基于人群的回顾性队列研究，将 MSIS 和 SYSVAK 与大流行流感疫苗接种作为暴露因素，将实验室确诊的大流行流感作为结局因素进行链接。我们按周测量 VE，并将免疫的两个阈值定义为八天和十五天。
当考虑将接种疫苗后十五天或更长时间作为免疫阈值时，每周 VE 范围为 77%至 96%，当考虑八天或更长时间作为免疫阈值时，VE 范围为 73%至 94%。总体而言，有 157 人在接种疫苗后八天或更长时间内感染了大流行性流感（每 100000 名接种者中有 8.4 人），其中 58 人在接种疫苗后十五天或更长时间内发病（每 100000 名接种者中有 3.0 人）。大多数疫苗失败发生在疫苗接种运动的最初几周。超过 30%的疫苗失败发生在 10 岁以下的人群中。
拥有包含特定疾病和疫苗接种数据的健康登记处，可以以简单快捷的方式估计 VE。无论选择何种免疫阈值，VE 均较高。我们鼓励其他国家的公共卫生当局建立此类登记处。考虑在现有的登记处中包含基础疾病信息也很重要，以便能够进行更完整的 VE 估计。
