Swedish Institute for Communicable Disease Control, 171 82 Solna, Sweden.
Vaccine. 2012 May 2;30(21):3239-47. doi: 10.1016/j.vaccine.2011.10.089. Epub 2011 Nov 15.
Shortly after pertussis vaccination was reintroduced in Sweden in 1996, an intensified pertussis disease surveillance programme was set up. In this study, we report on in-depth analyses of age-dose-number-specific incidences and the rate of pertussis hospitalisation for children with no, 1 or 2 doses of an acellular pertussis vaccine before pertussis disease. Vaccine coverage, the timeliness of childhood vaccination and the effect of later than scheduled pertussis vaccination(s) are also examined.
Children with notified laboratory-confirmed (culture or PCR) pertussis disease were evaluated among the surveillance population of about 1 million infants, born between 1996 and 2007 and followed for pertussis disease from October 1997 to December 2007, for nearly 6 million person-years. Birth and vaccination dates of the diseased children are known from the surveillance programme. To estimate denominators of the age-dose-number-specific pertussis incidences, we used birth and vaccination dates from a vaccine trial with more than 72,000 infants combined with national pertussis vaccine coverage data for children in the surveillance population.
For infants from 3 to <5 months of age, the incidence of pertussis disease with at least 14 days of cough decreased from 264/100,000 for unvaccinated infants to 155/100,000 for infants with one dose of a pertussis vaccine prior to onset of the disease. In the age range 5 to <12 months, the age-dose specific incidences were 526, 95, and 24/100,000 for infants with no, 1 and 2 doses, respectively. The rate of hospitalisation for infants with 1 dose of a pertussis vaccine prior to onset of the disease was significantly lower than for unvaccinated infants of the same age. For many infants, there is a delay in administration of the vaccine doses according to the regular 3-5-12 month schedule (which has been the case for many years). Hypothetically, if all infants had been vaccinated exactly on schedule, we would expect about 28% fewer pertussis cases with at least 14 days of cough and 38% fewer hospitalisations due to pertussis, of cases possible to influence by vaccinations on schedule.
Pertussis vaccination had a significant effect among infants already after the first dose. This is particularly important for premature infants and infants with severe respiratory and cardiac diseases. A moderate decrease in the incidence of pertussis disease in infants and rate of hospitalisation could be expected if primary vaccinations were carried out closer to the scheduled time than is currently the practice in Sweden.
1996 年瑞典重新引入百日咳疫苗后不久，建立了强化百日咳疾病监测计划。在这项研究中，我们报告了深入分析年龄剂量数特异性发病率和无细胞百日咳疫苗接种前发生百日咳疾病的儿童因百日咳住院的比率。还检查了疫苗覆盖率、儿童疫苗接种的及时性以及晚于预定百日咳疫苗接种的效果。
在大约 100 万婴儿的监测人群中，评估了通知实验室确诊（培养或 PCR）百日咳疾病的儿童，该监测人群于 1997 年 10 月至 2007 年 12 月期间进行了百日咳疾病监测，随访近 600 万人年。患病儿童的出生和接种日期可从监测计划中获得。为了估计年龄剂量数特异性百日咳发病率的分母，我们使用了一项针对 72,000 多名婴儿的疫苗试验中的出生和接种日期，并结合了监测人群中儿童的百日咳疫苗覆盖率数据。
对于 3 至<5 个月大的婴儿，至少有 14 天咳嗽的百日咳疾病发病率从未接种疫苗的婴儿的 264/100,000 降至疾病发病前接种一剂百日咳疫苗的婴儿的 155/100,000。在 5 至<12 个月的年龄范围内，无、1 剂和 2 剂百日咳疫苗的年龄剂量特异性发病率分别为 526、95 和 24/100,000。发病前接种一剂百日咳疫苗的婴儿的住院率明显低于同年龄未接种疫苗的婴儿。对于许多婴儿来说，疫苗接种剂量的延迟与常规的 3-5-12 个月接种时间表相符（多年来一直如此）。假设所有婴儿都能按计划按时接种疫苗，那么我们预计至少有 14 天咳嗽的百日咳病例会减少 28%，可通过按时接种疫苗影响的病例住院率会减少 38%。
百日咳疫苗接种在第一剂后对婴儿产生了显著影响。这对于早产儿和患有严重呼吸道和心脏疾病的婴儿尤为重要。如果初级疫苗接种更接近瑞典目前的做法，而不是接近预定时间，则可以预期婴儿百日咳疾病的发病率和住院率会适度降低。
