一起初中水痘突发公共卫生事件的疫苗保护效果评价

目的评价上海市徐汇区2013年某初中水痘突发公共卫生事件中既往水痘疫苗以及应急接种水痘疫苗的免疫效果,为有效控制学校水痘暴发疫情提供依据。方法采用现场流行病学方法收集徐汇区某初中水痘疫情相关资料和该校学生既往水痘疫苗接种史及应急接种情况,计算水痘疫苗保护效果。结果在2013-10-03/12-19该校累计报告27例临床诊断水痘病例,罹患率为3.82%,发病学生主要集中在初二年级,年级水痘罹患率为14.14%。该校707名学生中有558名曾接种水痘疫苗,疫苗接种率为78.93%。经趋势检验,随着年级提升学生水痘疫苗接种率呈下降趋势(χ2=6.56,P0.05)。以水痘疫苗接种史为暴露因素,初二年级病例组接种率为66.67%,对照组接种率为76.74%,病例组与对照组暴露比值比(Odds ratio,OR值)为0.50(95%CI:0.21~1.22),总保护效率为49.62%(95%CI为-22.26%~79.24%)。该校分别于首发病例发病后第13天和第19天对首发班级和全校易感学生进行水痘疫苗的应急免疫,全校应急免疫率为41.38%,应急接种有效率VE应急为53.66%(95%CI为-42.22%~84.90%)。结论该校水痘突发公共卫生事件中,首发病例未及时隔离和疫情期间学校运动会的召开是导致水痘在该校初二年级蔓延的主要原因。水痘疫苗接种距疫情时间间隔过长可能是水痘疫苗未能在本次疫情中起到保护作用的原因之一。在首发病例发病后尽早对易感学生进行水痘疫苗应急接种,可更迅速地形成人群免疫屏障,有效控制暴发疫情。     

无锡市某小学1起水痘暴发疫情的流行病学调查

目的 通过分析1起小学水痘暴发疫情的流行病学特征、影响因素,为制定有效防控水痘疫情的措施提供依据.方法 采用现场流行病学调查方法,确定病例定义,开展病例搜索,用描述性流行病学方法进行统计分析.结果 本起疫情共发生29例水痘病例,罹患率为1.75％,均为学生.病例分布在2个班级,班级内与首发病例相邻座位的学生(62.50％)发病风险高于间隔≥1座学生(27.42％)(X2=6.91,P＜0.05).2个班级罹患率分别为52.50％、20.00％,应急接种率分别为16.00％、85.71％,应急接种率有差异导致最终罹患率差异有统计学意义.29例病例中,62.07％接种过1剂次水痘疫苗,其他均无水痘疫苗接种史.结论 1剂次水痘疫苗效果不佳,建议适龄儿童接种2剂次水痘疫苗;应急接种率低是造成此次疫情持续发展的主要原因,一旦发生水痘疫情,应急接种应充分动员、尽快开展.     

上海市某小学水痘暴发调查及应急接种的血清学评价

目的 对某小学水痘暴发疫情进行流行病学调查,并对水痘疫苗应急接种效果进行血清学评价,为学校水痘暴发控制提供参考.方法 收集病例病史资料及病例所在年级学生疫苗接种史和既往水痘病史,对应急接种对象分别于接种前、接种后2周、4周采集手指末梢血,用定量酶联免疫吸附试验(Enzyme-linked Immunosorbent Assay,ELISA)检测水痘IgG.结果 本次暴发共发生水痘13例,病例所在的年级罹患率为9.29％,有接种史的罹患率为7.58％,无接种史的罹患率为33.33％,无接种史的罹患率显著高于有接种史者,疫苗保护率(Vaccine Efficacy,VE)为77.26％.应急接种前接种对象抗体阳性率为72.73％,免后2周、4周抗体阳性率均为100％.免后抗体浓度明显高于免前抗体浓度,且免后2周抗体浓度明显高于免后4周抗体浓度.结论 水痘疫苗能有效预防水痘,建议对接种1剂水痘疫苗的儿童间隔满3年后再推荐加强接种1剂.水痘疫苗的应急接种能迅速提高易感者体内的抗体水平,有助于水痘暴发的控制.     

苏州市吴中区小学2017-2018年水痘暴发应急处置效果比较

观察现行水痘疫苗接种策略下小学水痘疫情暴发情况,评价应急接种对暴发疫情控制的效果.方法 收集2017—2018年冬春季苏州市吴中区小学水痘暴发病例的流行病学资料,利用传染病报告信息管理系统、学校因病缺课信息系统比较应急接种法和传统应急停课法开展后水痘病例的续发感染情况.结果 应急接种实验组(187 人) 既往水痘疫苗接种率为78.5%,平均应急接种率为75.0%,续发罹患率为5.0%; 停课对照组(95 人) 既往水痘疫苗接种率为 53.2%,续发罹患率为13.6%.在控制了既往疫苗接种史后,停课对照组的水痘病例续发危险度为应急实验组的5.20 倍 (95%CI = 1.30~ 20.20,P= 0.02).结论 接种一针剂水痘疫苗未在儿童中形成有效免疫屏障.较传统的应急停课方案相比,应急接种能够提高暴发疫情控制效果,降低间接疾病负担.     

三水区某小学流行性腮腺炎暴发疫情的调查分析

目的通过调查三水区一起小学流行性腮腺炎暴发疫情,分析疫情发生原因,探讨含腮腺炎成分疫苗接种对疫情控制的影响。方法根据传染病报告信息管理系统流行性腮腺炎监测数据及现场流行病学调查资料,分析三水区某小学流行性腮腺炎暴发疫情特点,疫情发生原因及含腮腺炎成分疫苗接种水平对腮腺炎发病的影响。结果三水区某小学发生流行性腮腺炎暴发疫情,疫情持续64d,累计42名学生发病,罹患率1.38%,六年级学生罹患率高于其他年级学生罹患率(χ~2=124.54,P0.05),六年级学生既往接种1剂次含腮腺炎成分疫苗保护率为46.67%,疫情暴发期间,六年级学生应急接种率为29.59%,应急接种疫苗保护率为100%,调查发现共有6例流腮病例学校未及时隔离是暴发疫情发生的主要影响因素。结论首发病例没有及时隔离,疫情期间学校组织班级交叉考试,可能是该起暴发疫情发生的主要原因,六年级学生既往接种1剂次含腮腺炎成分疫苗保护效果不理想、应急接种率低、是该起疫情持续蔓延的重要因素。     

一起小学水痘暴发疫情的疫苗保护效果研究

目的分析水痘疫苗对控制水痘暴发疫情的保护效果。方法选取发生水痘疫情的某小学的学生作为研究对象,采用回顾性队列研究方法分析接种疫苗与水痘发病的关系,计算疫苗保护率。结果对能明确接种史并且未患过水痘的1 216名学生进行回顾性队列研究,结果显示,水痘疫苗接种组与未接种组罹患率差异有统计学意义(P0.01),疫苗总体保护率为58%,接种2剂次疫苗保护率为100%;接种水痘疫苗后3年内保护率为100%,第4年开始下降。结论接种水痘疫苗是控制水痘暴发疫情的有效策略,尤其要提高2剂次水痘疫苗的接种率。     

北京市西城区2007-2009年学校水痘疫情分析

目的了解北京市西城区学校水痘的流行病学特征,为控制水痘提供科学依据。方法对2007-2009年北京市西城区疾病预防控制中心收集的水痘病例个案调查表进行分析。结果 2007-2009年西城区学校累计发生水痘758例,发病水平和流行强度逐年下降。水痘全年均有发病,有2个高峰和2个低谷。小学生水痘年平均发病率为4.99‰,高于中学生的2.26‰。有免疫史的病例占60.03%,接种过水痘疫苗的病例临床症状较轻。结论接种疫苗可减少水痘重症病例。发生疫情应急接种范围可扩大至免疫史超过5 a者。     

不同应急接种策略教学机构水痘聚集性疫情防控效果

探讨水痘疫苗应急接种启动时间、应急前班级新发水痘病例数以及应急接种率对教学机构水痘聚集性疫情的防控效果.方法 前瞻性观察2013-2016年上海市徐汇区教学机构开展水痘疫苗应急接种的聚集性疫情,采用描述性流行病学方法评价不同应急接种策略对疫苗应急接种保护效果和疫情防控效果的影响.结果 2013-2016年徐汇区共有129起水痘聚集性疫情开展应急接种,其中有8 462名学生符合应急接种标准,应急接种率为55.9%(4 730/8 462).应急接种后,应急接种组学生续发水痘罹患率为1.5%(71/4 659),低于未应急接种组的3.2%(119/3 613)(X2=27.10,P<0.01),应急接种总体保护效果为53.7%(95% CI=37.7%~65.6%).班级应急接种率≥80%的疫苗保护效果高于<80%班级学生(84.8%,45.7%).应急接种前班级新发水痘病例≤1例的班级出现续发病例的比例低于1例病例的班级(22.9%,45.5%)(X2=15.04,P<0.01),班级疫情持续时间(20.9 d)也短于1例病例的班级(23.8 d)(P<0.01).结论 在教学机构水痘聚集性疫情期间开展水痘疫苗应急接种的措施切实有效.为获得更高的应急接种效益,建议尽早开展水痘疫苗应急接种并提高群体应急接种率.     

上海市部分地区儿童水痘疫苗免疫后流行病学效果观察

[目的]观察水痘疫苗接种情况和接种水痘疫苗1~7年后的水痘发病情况。[方法]在本市部分地区选择接种组和未接种组儿童,采用统一调查问卷调查水痘疫苗接种情况和水痘发病情况。[结果]调查地区儿童水痘疫苗累积接种率为4.12%,12岁以下人群为26.90%。1999~2005年接种组总发病率为1.00%,未接种组为4.35%,水痘疫苗接种保护率为77.0%;各年接种组发病率分别为1.62%、2.06%、0.29%、0.43%和0.66%,疫苗接种保护率在67.9%~90.3%之间;接种进口和国产水痘疫苗后水痘发病率分别为0.8%和1.0%,疫苗接种保护率分别为81.6%和75.3%。[结论]本市儿童水痘疫苗接种率呈上升趋势。水痘疫苗对接种者具有较好的保护率,进口和国产水痘疫苗的保护率相似。     

北京市一起小学水痘暴发疫情调查

目的了解北京市某小学水痘疫情的性质和原因,为有效防控小学生水痘疫情提供依据。方法采取现场流行病学调查,对北京市某小学30例水痘病例流行病学资料进行分析。结果本次疫情共有30名学生发病,罹患率为3.09%。86.67%的病例有免疫史,有免疫史者罹患率为2.89%,无免疫史者为9.09%。无免疫史和免疫史≥5a是主要发病人群;接种时间5a预防效果明显,≥5a预防作用逐渐减弱。结论疫苗接种时间较长、人群免疫水平较低是某小学水痘暴发疫情发生的主要原因。建议提高接种率,适时接种第二剂水痘疫苗。     

2006—2008年北京市海淀区中小学校及幼托园水痘暴发疫情分析

目的了解北京市海淀区中小学校和幼托园水痘暴发疫情的流行病学特征。方法利用描述流行病学方法,根据国家疾病监测报告管理系统,对海淀区2006—2008年报告的中小学校和幼托园水痘暴发疫情资料进行分析。结果海淀区2006—2008年中小学校和幼托园共报告水痘暴发疫情21起,累计发病317例,无死亡病例,小学水痘暴发疫情16起,占总数的76．2％;暴发疫情主要集中在3～6月、11月和12月;2006—06以后对疫情发生单位中年龄在15岁及以下易感者进行水痘疫苗的免费应急接种,接种率92．6％～100％;暴发疫情时间持续最长65d,最短5d,平均28d（中位数）;暴发病例中有水痘疫苗明确免疫史的占41．96％,无免疫史的占49．84％,免疫史不详的占8．20％。结论2006—2008年海淀区报告的中小学校和幼托园水痘暴发疫情逐年增多,小学的水痘暴发疫情比例较大,说明小学生是水痘暴发疫情控制的重点人群,需采取有针对性的控制措施。     

A varicella outbreak in a school with high one-dose vaccination coverage, Beijing, China

Background

Varicella vaccine is available in the private sector in China, with a single dose currently recommended for children aged ≥12 months. We investigated a varicella outbreak in a school in Beijing with high varicella vaccination coverage to describe the outbreak, examine risk factors for vaccine failure, and calculate vaccine effectiveness.

Methods

A varicella case was defined as an acute generalized maculopapular rash without other apparent cause in a student without prior varicella attending the elementary school during August 30–December 28, 2010. Varicella among vaccinated students (breakthrough varicella) was defined as varicella occurring >42 days after vaccination. Students’ vaccination status was verified with immunization records and clinical presentations were collected from health care practitioners.

Results

Of the 951 students, 934 (98%) had no prior varicella history. Among these students, 916 had received 1 dose of varicella vaccine and 2 had received 2 doses (98% vaccination coverage) before the outbreak. A total of 87 cases occurred during the outbreak; most had breakthrough varicella (86/87, 99%) and mild disease (83/87, 95%). Age at vaccination (<15 months vs. ≥15 months) and time since vaccination before outbreak (<5 years vs. ≥5 years) were not associated with development of breakthrough varicella. Single-dose varicella vaccination was 89% effective in preventing any varicella and 99% in preventing moderate/severe varicella.

Conclusion

Single-dose varicella vaccination is highly effective in reducing varicella incidence and mitigating disease severity, but not high enough to prevent outbreak. A two-dose program might help to prevent varicella outbreaks in Beijing.     

浙江省宁波市某区2010--2012年水痘突发疫情中疫苗保护效果分析

目的了解水痘疫苗接种在水痘突发疫情中的保护效果。方法收集宁波市某区2010--2012年水痘疫情报告信息,计算接种疫苗与否水痘发病率的比值比（OR）,疫苗保护率及疫苗的效果指数。随机抽取未出现疫情的小学生109名,使用ELISA法进行水痘IgG抗体检测,评价疫苗接种的效果。结果该区2010—2012年共发生3起一般水痘突发事件,共报告病例40例（无死亡病例）,均为幼托儿童和小学生。疫情发生所在班级学生161人,接种疫苗和未接种疫苗者发病率比较差异有统计学意义（19．42％：59．09％,X2=16．01,P〈0．01）,DR值为0．17（95％CI：0．07~0．43）。疫苗总体保护率为67．13％,疫苗效果指数为3．05。未出现疫情的109名学生中,有77人接种过疫苗,但水痘IgG抗体检测显示,仅40．26％（31／77）抗体阳性。结论幼托儿童、小学生接种水痘疫苗可有效降低水痘的发病率,水痘疫苗的质量及实际保护效果需进一步评估。     

Evaluation of varicella vaccine effectiveness during outbreaks in schools or nurseries by cross-sectional study

ObjectiveThe aim of this study was to elucidate vaccine effectiveness (VE) during varicella outbreaks in schools and nurseries in Japan.MethodsAn outbreak was defined as emergence of three or more cases of varicella within 21 days at the same institute. Clinical information such as varicella vaccination status, and history of varicella was collected. If a child had varicella during the outbreak, information about absences, fever, and disease severity was collected.ResultsFrom September 2018 to January 2020, four outbreaks were reported around our institute from three elementary schools and one nursery. A total of 676 children were analyzed in this study. Seventy-six children (11.2%) were unvaccinated, 309 (45.7%) had received one dose of vaccine, and 291 (43.0%) had received two doses. Most children in Pre-K2 (1–2 years old) to Pre-K6 (5–6 years old), who were the targets of the national immunization schedule, received two doses. Meanwhile, most children older than third grade received single dose. Seventy-five children (11.1%) had varicella. Varicella prevalence from Pre-K5 to the third grade was greater than 10%. The adjusted VEs of single- and two-dose of varicella vaccine were 57.8% and 89.0%. The number of days absent was significantly longer in unvaccinated children than single-dose recipients (P = 0.0145). Unvaccinated children had significantly more severe skin eruptions than single-dose recipients (P = 0.0046) and two-dose recipients (P = 0.0258).ConclusionsAlthough VEs of single-dose varicella vaccination during outbreaks was not high, the VE of two-dose vaccination was similar to that in a previously reported case-control study.     

Varicella outbreak in a highly-vaccinated school population in Beijing,China during the voluntary two-dose era

BackgroundTwo-dose varicella vaccination has been available in Beijing since 2012 in the private sector. We investigated a varicella outbreak in a highly vaccinated elementary school population.MethodsA cohort study was carried out and a varicella case was defined as an acute onset of generalized maculopapulovesicular rash without other apparent cause in a student attending the school from March 29 through May 17, 2015. Breakthrough varicella was defined as varicella >42 days after the last vaccine dose among both 1- or 2-dose varicella vaccine recipients. Vaccination information was collected from immunization records; information on prior varicella and clinical presentations was collected by surveying students’ parents.ResultsOf the 1056 students in the school, 1027 (97.3%) reported no history of varicella. Prior to the outbreak, 98.6% of students had received ≥1 dose of varicella vaccine, and most (63.2%) students received two doses. Twenty varicella cases were identified for an overall attack rate of 2.0%. Half of the cases occurred in the classroom of the index case-patient, a two-dose recipient who was not isolated after symptom onset. Breakthrough varicella accounted for 95% of cases (19/20) with attack rates of 14.3% (1/7), 1.6% (6/362) and 2.0% (13/649) among unvaccinated, one-dose, and two-dose students, respectively. Most case-patients (18/20, 90%) had <50 lesions. No difference in clinical presentations was found between one-dose and two-dose recipients with breakthrough varicella.ConclusionModerate two-dose varicella vaccine coverage was insufficient to prevent a varicella outbreak. Two-dose recipients with breakthrough varicella are contagious. High two-dose varicella vaccine coverage and timely isolation of cases may be needed for varicella outbreak prevention in the two-dose era.     

应用青岛市6-13岁人群病例对照研究评价水痘减毒活疫苗保护效果

目的评价青岛市儿童水痘减毒活疫苗(Varicella attenuated live vaccine,VarV)的保护效果(Vaccine effectiveness,VE)。方法采用病例对照研究设计,选择青岛市14所学校48个班级的6-13岁学生,将2013-2018年有、无水痘发病史的学生分别纳入病例组、对照组,收集水痘发病和VarV接种信息,计算VarV的VE。结果本研究纳入532例水痘病例和1 596例对照。VarV的总体VE为51.7%(95%CI:40.9%-60.6%);接种1剂次、2剂次VarV的VE分别为44.4%(95%CI:31.5%-54.8%)、81.8%(95%CI:71.0%-88.6%)。在接种1剂次VarV后0-2、3-4、5-6、7-8、≥9年的VE分别为90.1%、64.8%、50.2%、40.8%、34.5%。结论儿童接种1剂次VarV的保护效果较差,且随着接种后时间的推移而递减;建议适龄儿童接种2剂次VarV,并纳入国家免疫规划。     

Single-dose varicella vaccine effectiveness in school settings in China

Background

Varicella vaccine has been available in the private sector in China for a decade as a single-dose regimen, but varicella vaccine effectiveness (VE) has not been fully examined in school settings yet.

Methods

A matched case–control study was carried out in elementary schools and daycares in Tai’an prefecture, Shandong province, China. Clinical diagnosis of varicella and breakthrough disease was used for this study. Four controls were randomly selected from classmates; two from classmates of the case and two from another class of the same grade without cases. Vaccination status, date of vaccination, and vaccine product received if vaccinated were collected from home and clinic immunization records. Vaccination status of all students in schools/daycares with varicella cases from home immunization records or parental recall was used to calculate vaccination coverage.

Results

The overall varicella VE was 83.4% (95% confidence interval 71.4–90.3%). Receipt of varicella vaccine five years or more years before the outbreak was significantly associated with breakthrough varicella (odds ratio = 4.7, P < 0.001), while age at vaccination (<15 vs. ≥15 months) was not (odds ratio = 1.5, P = 0.62). Varicella vaccination coverage was 41% with substantial variation across schools (range of 0–93.8%).

Conclusions

Single-dose varicella vaccine is highly effective in school settings. Maintaining limited vaccination coverage might shift varicella disease burden to older individuals, who are more prone to develop severe outcomes if varicella occurs.     

Immunization coverage and natural infection rates of vaccine-preventable diseases among children by questionnaire survey in 2005 in Japan

We performed questionnaire survey in 2005, just before the introduction of the MR vaccine, concerning child vaccination and/or infection history for measles, mumps, rubella, varicella, influenza, diphtheria-pertussis-tetanus (DPT), BCG, and Japanese encephalitis. The vaccination rate against measles and rubella did not exceed 95% at any age levels. As a result, children who had contracted measles and/or rubella were observed at all age levels. The vaccination rate was 95% or higher only for BCG and DPT. The vaccination rates for influenza, mumps, and varicella, although vaccination against which diseases was being performed voluntarily, were low, and outbreaks of these diseases were expected to persist. The vaccination rates at a low level for these infectious diseases might be one of the most possible risk factors to the high prevalence of the diseases in nursery schools (daycare centers), kindergartens, and elementary schools all over Japan.     

上海市奉贤区2012-2018年学校和托幼机构水痘疫情流行病学分析

分析上海市奉贤区2012-2018年学校和托幼机构水痘疫情流行病学特征,为制定水痘防控措施提供参考依据.方法 对上海市奉贤区2012-2018年水痘疫情资料进行描述性流行病学分析,百分率的比较采用x2检验.结果 上海市奉贤区2012-2018年共报告6 727例水痘病例,年平均发病率为85.34/10万;报告水痘暴发疫情和突发公共卫生事件66起,水痘病例741例,其中426例(57.49%)为水痘突破病例,平均间隔时间为(6.78±2.79)年,接种后间隔3~9年发病人数较为集中,其中接种疫苗后5年为高峰.发病时间高峰在每年的10-12月.发病年龄以5~11岁和15~ 17岁为主,男性病例多于女性病例,托幼儿童和小学生是水痘的高发人群.报告及时性和疫情持续时间呈正相关(r=0.52,P<0.05).结论 上海市奉贤区秋冬季小学水痘疫情高发,且病例中突破病例较多,应急接种可有效控制疫情蔓延.建议加大2剂次水痘疫苗免疫程序宣传力度,提高儿童家长水痘疫苗接种意识.     

北京市安定镇15岁以下人群水痘疫苗接种情况

目的了解北京市安定镇15岁以下人群水痘疫苗接种情况,为提高水痘疫苗接种率和控制水痘疫情提供依据。方法对北京市安定镇全部15岁以下人群通过免疫规划信息系统和查阅应急接种表,对水痘疫苗接种史进行描述性分析。结果共调查3 461人,水痘疫苗接种率66.57%(76.62～34.39%),1～7岁组接种率维持在较高水平(71.64%～76.62%),年龄组接种率差异有统计学意义(P0.01)。该地人群与外地人群接种率分别为60.78%、67.56%,差异有统计学意义(P0.01)。进口水痘疫苗接种率随年龄下降而增加;托幼机构和小学、中学水痘疫苗接种率分别为78.72%、63.84%、41.40%,差异有统计学意义(P0.01)。应急接种占总接种数的42.52%;小、中学生应急接种分别占该年龄组接种总数的52.67%、94.76%。结论该镇要加强15岁以下人群水痘疫苗接种宣传,提高接种率,控制托幼机构和学校水痘疫情。