Pediatrics:妊娠期注射百白破疫苗优于产后接种

　　美国CDC的一份最新报告显示，与产后立即接种疫苗相比，妊娠期接种百白破疫苗可以减少新生儿发病、住院和死亡人数，而且性价比也更高。该研究于2013年5月27日在线发表于《儿科学》(Pediatrics) 杂志。

　　 该研究纳入全国法定传染病数据库的信息，估算了婴儿百日咳的病例数，基于婴儿百日咳62.6/100,000的年发生率，估算了住院治疗、呼吸道疾病、脑病和死亡的发生几率。假设妊娠期接种覆盖率为72%，产后接种的覆盖率也为72%。此外，假设疫苗的有效率为85%，母源抗体的转移率为100%，婴儿2月龄内的保护率为60%。产后接种的保护效应会延迟2周出现，因为需要经过这段时间产妇体内才能形成足够多的抗体。

　　结果显示，如果不接种疫苗，每年大约会出现3,041例婴儿百日咳，导致1,463例住院和22例死亡。相比之下，单纯产后接种每年可以避免596例婴儿百日咳，较之基础病例数减少了20%。产后接种加“蚕茧接种” 每年可以避免987例，使发病率下降32%。妊娠期接种每年能预防的病例数更多，大约为1,012例，发病率下降了33%。与产后接种相比，妊娠期接种可以让更多的婴儿免于死亡和住院(与不接种相比，死亡人数减少49%，住院人数减少38%)。此外，妊娠期接种每年可以挽救396个质量调整生命年(QALY)，而产后接种加“蚕茧接种” 每年只能挽救253个QALY。

　　研究者还补充，除了这些优势之外，妊娠期接种的可行性也优于产后接种，因为在现有的产前检查程序内就能轻松实现妊娠期接种。相比之下，让产妇尤其是婴儿父亲、祖父/祖母和同胞兄妹接种则更加困难。妊娠期接种的成本大约为1.71亿美元/年，而产后接种加“蚕茧接种”的成本则高达5.13亿美元/年。妊娠期接种每挽救1个QALY的成本大约为41.4万美元，远远低于产后接种(120万美元)加“蚕茧接种”(200万美元)的成本。

　　解释“蚕茧接种”：即与婴儿有密切接触的家庭成员接种疫苗 。

Pregnancy Dose Tdap and Postpartum Cocooning to Prevent Infant Pertussis: A Decision Analysis
BACKGROUND: Infants <2 months of age are at highest risk of pertussis morbidity and mortality. Until recently, the US Advisory Committee on Immunization Practices (ACIP) recommended protecting young infants by “cocooning” or vaccination of postpartum mothers and other close contacts with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed (Tdap) booster vaccine. ACIP recommends pregnancy vaccination as a preferred and safe alternative to postpartum vaccination. The ACIP cocooning recommendation has not changed.
METHODS: We used a cohort model reflecting US 2009 births and the diphtheria-tetanus-acellular pertussis schedule to simulate a decision and cost-effectiveness analysis of Tdap vaccination during pregnancy compared with postpartum vaccination with or without vaccination of other close contacts (ie, cocooning). We analyzed infant pertussis cases, hospitalizations, and deaths, as well as direct disease, indirect, and public health costs for infants in the first year of life. All costs were updated to 2011 US dollars
RESULTS: Pregnancy vaccination could reduce annual infant pertussis incidence by more than postpartum vaccination, reducing cases by 33% versus 20%, hospitalizations by 38% versus 19%, and deaths by 49% versus 16%. Additional cocooning doses in a father and 1 grandparent could avert an additional 16% of cases but at higher cost. The cost per quality-adjusted life-year saved for pregnancy vaccination was substantially less than postpartum vaccination ($414 523 vs $1 172 825).
CONCLUSIONS: Tdap vaccination during pregnancy could avert more infant cases and deaths at lower cost than postpartum vaccination, even when postpartum vaccination is combined with additional cocooning doses. Pregnancy dose vaccination is the preferred alternative to postpartum vaccination for preventing infant pertussis.