Zöldi Viktor, Sane Jussi, Nohynek Hanna, Virkki Maria, Hannila-Handelberg Tuula, Mertsola Jussi
Department of Health Security, National Institute for Health and Welfare (THL), Helsinki, Finland; European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
Department of Health Security, National Institute for Health and Welfare (THL), Helsinki, Finland.
Vaccine. 2017 Sep 18;35(39):5249-5255. doi: 10.1016/j.vaccine.2017.08.008. Epub 2017 Aug 18.
In 2005, in Finland, the whole-cell pertussis vaccine was replaced by acellular given at 3-5-12months, and boosters at 4 and 11-15years of age. From July 2012, military conscripts have been offered a pertussis booster dose. Conscription is mandatory for Finnish men, and >95% were 19-21years old when enrolled during 2012-2015. We describe the epidemiology of pertussis in Finland during 1995-2015, and show the indirect effect of the booster in conscripts on pertussis incidence in the Finnish population.
We extracted data on laboratory confirmed notified pertussis cases from the National Infectious Diseases Register. We calculated annual incidence using as denominator population data and incidence rate ratios (IRR) using Poisson regression.
The overall pertussis incidence peaked in 2004 (31/100,000) and was lowest in 2015 (3.0/100,000), with 66 reported cases in <3months infants in 2004 versus 6 in 2015. The majority of the cases were female (59%) with a male-to-female case ratio of 1:1.5. Cases were spread throughout the year with highest incidence during August-February. Among the 19- to 21-year-olds in the general population, incidence decreased from 49/100,000 in 2011 to 0.51/100,000 in 2015 (IRR=0.01; 95%CI, 0.00-0.16). Among the same age group, comparing the 3.5-year period before and after July 2012, incidence decreased from 33/100,000 to 5.3/100,000 (IRR=0.16; 95%CI, 0.06-0.40) in males and from 16/100,000 to 5.0/100,000 (IRR=0.31; 95%CI, 0.11-0.84) in females.
Implementation of the pertussis booster dose in Finnish military conscripts was followed by a significant decrease in pertussis incidence both among the 19- to 21-year-old males and females, possibly reflecting herd immunity effect. Together with booster doses in adolescents this has resulted in low incidence in the whole population including infants. Our results support the implementation of the booster dose for conscripts. We recommend continuing monitoring pertussis epidemiology to optimize pertussis vaccination strategies in Finland.
2005年，芬兰将全细胞百日咳疫苗替换为在3、5、12月龄接种的无细胞百日咳疫苗，并在4岁以及11 - 15岁时进行加强免疫。自2012年7月起，已为应征入伍者提供百日咳加强剂量疫苗。芬兰男性必须服兵役，在2012 - 2015年入伍期间，超过95%的应征者年龄在19 - 21岁。我们描述了1995 - 2015年芬兰百日咳的流行病学情况，并展示了对应征者进行加强免疫对芬兰人群百日咳发病率的间接影响。
我们从国家传染病登记处提取了实验室确诊的百日咳报告病例数据。我们使用人口数据作为分母计算年发病率，并使用泊松回归计算发病率比（IRR）。
百日咳总体发病率在2004年达到峰值（31/100,000），在2015年降至最低（3.0/100,000），2004年3个月以下婴儿中有66例报告病例，而2015年为6例。大多数病例为女性（59%），男女病例比为1:1.5。病例全年均有分布，8月至次年2月发病率最高。在一般人群的19 - 21岁年龄组中，发病率从2011年的49/100,000降至2015年的0.51/100,000（IRR = 0.01；95%CI，0.00 - 0.16）。在同一年龄组中，比较2012年7月前后3.5年的时间，男性发病率从33/100,000降至5.3/100,000（IRR = 0.16；95%CI，0.06 - 0.40），女性发病率从16/100,000降至5.0/100,000（IRR = 0.31；95%CI，0.11 - 0.84）。
对芬兰应征入伍者实施百日咳加强免疫后，19 - 21岁男性和女性的百日咳发病率均显著下降，这可能反映了群体免疫效应。与青少年的加强免疫一起，这使得包括婴儿在内的整个人口的发病率较低。我们的结果支持对应征者实施加强免疫。我们建议继续监测百日咳流行病学情况，以优化芬兰的百日咳疫苗接种策略。
