Brophy J, Baclic O, Tunis M C
Children's Hospital of Eastern Ontario, Ottawa, ON.
Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, OttawaON.
Can Commun Dis Rep. 2018 Mar 1;44(3-4):91-94. doi: 10.14745/ccdr.v44i34a04.
In Canada, pertussis is an endemic and cyclical disease, with peaks occurring at two- to five-year intervals. Although pertussis incidence varies by age group, unvaccinated or undervaccinated infants are at greatest risk of infection and associated complications. Since the last National Advisory Committee on Immunization (NACI) recommendations published in 2014, new evidence on the safety and effectiveness of tetanus toxoid, reduced diphtheria toxoid and reduced acellular pertussis (Tdap) vaccine administration in pregnancy has become available.
To provide guidance on maternal immunization in pregnancy as a strategy to reduce disease incidence and severe outcomes (defined as hospitalization or death) from pertussis infection in infants less than 12 months of age.
The NACI reviewed evidence on the burden of disease in Canada, vaccine safety and immunogenicity and vaccine effectiveness in jurisdictions that have implemented maternal immunization programs. A total of 59 articles were identified, retrieved and included in the literature review to inform this statement.
In the majority of reviewed studies, post immunization increases in antibody levels resulted in more than 90% of women achieving anti-PT levels greater than or equal to 10 IU/ml one month following immunization. In infants, maternal immunization was found to result in increased pertussis antibody concentrations. In the majority of studies, following the receipt of the fourth diphtheria, tetanus and pertussis (DTaP) dose after 15 months of age, no statistically significant differences in antibody levels and avidity were observed between infants whose mothers received Tdap in pregnancy and those whose mothers did not receive Tdap in pregnancy. No major maternal or infant safety issues, including pregnancy outcomes, were reported in the reviewed literature. Effectiveness of maternal Tdap immunization in pregnancy was estimated to be over 90% against pertussis in infants younger than two months of age, with no deaths observed among infants whose mothers received Tdap prior to 36 weeks of pregnancy. Maternal immunization with Tdap in pregnancy also resulted in a reduction in infant disease severity and hospitalization. Vaccine effectiveness was also reported to persist after the receipt of the first three DTaP doses, with immunization in pregnancy resulting in additional protection of up to 70% in children whose mothers received Tdap in pregnancy.
There is now strong evidence to support the NACI recommendation that immunization with Tdap vaccine should be offered in every pregnancy. This is ideally administered between 27 and 32 weeks of gestation but evidence also supports providing maternal Tdap over a wider range of gestational ages, from 13 weeks up to the time of delivery, in view of programmatic and unique patient considerations.
在加拿大，百日咳是一种地方性周期性疾病，每隔两到五年会出现发病高峰。尽管百日咳发病率因年龄组而异，但未接种疫苗或疫苗接种不足的婴儿感染及相关并发症的风险最高。自2014年发布上一次国家免疫咨询委员会（NACI）建议以来，关于破伤风类毒素、白喉类毒素含量降低的无细胞百日咳（Tdap）疫苗在孕期接种的安全性和有效性有了新证据。
为孕期母体免疫提供指导，作为降低12个月龄以下婴儿百日咳感染发病率和严重后果（定义为住院或死亡）的一项策略。
NACI审查了加拿大疾病负担、疫苗安全性和免疫原性以及已实施母体免疫计划的司法管辖区内疫苗有效性的相关证据。共识别、检索并纳入59篇文章进行文献综述，以为本声明提供参考。
在大多数综述研究中，免疫接种后抗体水平升高，超过90%的女性在免疫接种后一个月抗百日咳毒素（PT）水平达到或高于10 IU/ml。在婴儿中，发现母体免疫可使百日咳抗体浓度升高。在大多数研究中，15个月龄后接种第四剂白喉、破伤风和百日咳（DTaP）疫苗后，母亲在孕期接种Tdap的婴儿与母亲未在孕期接种Tdap的婴儿在抗体水平和亲和力方面未观察到统计学上的显著差异。综述文献中未报告重大的母体或婴儿安全问题，包括妊娠结局。据估计，孕期母体接种Tdap对两个月龄以下婴儿百日咳的有效性超过90%，在妊娠36周前母亲接种Tdap的婴儿中未观察到死亡病例。孕期母体接种Tdap还可降低婴儿疾病严重程度和住院率。据报告，在接种前三剂DTaP疫苗后，疫苗有效性依然存在，孕期免疫接种可为母亲在孕期接种Tdap的儿童提供高达70%的额外保护。
现在有强有力的证据支持NACI的建议，即每次怀孕时都应接种Tdap疫苗。理想情况下，应在妊娠27至32周之间接种，但鉴于计划安排和患者的特殊情况，有证据也支持在更广泛的孕周（从13周直至分娩时）为母体接种Tdap。
