福建省2019年水痘暴发事件及疫苗保护效果分析

目的 了解福建省2019年水痘暴发事件流行特征,评估水痘疫苗保护效果.方法 用描述性流行病学、回顾性队列研究方法进行分析.结果 福建省2019年报告水痘突发事件58起,均发生在学校.学生水痘疫苗平均接种率70.3％,2剂次接种率10.7％.学生共2 813人纳入队列研究,暴发疫情中水痘疫苗保护效果为54％(95％CI=...     

水痘疫苗在学校和幼儿园水痘暴发疫情中保护效力的回顾性队列研究

目的 评价水痘疫苗在学校和幼儿园水痘暴发疫情中的保护效力。方法 选择中山市2013-2014年有水痘暴发疫情的学校和幼儿园,采用回顾性队列研究方法评价水痘疫苗的保护效力。结果 共有1 278名学生纳入研究对象,水痘疫苗效力为52.7%（95% CI:43.3%～60.6%）;分层分析发现,接种年限为≤2年、3～年、5～年、7～年和≥9年的疫苗效力分别为71.0%（95% CI:57.7%～80.1%）、59.5%（95% CI:45.8%～69.7%）、52.6%（95% CI:33.7%～66.1%）、27.8%（95% CI:-11.5%～53.2%）和14.9%（95% CI:-20.6%～40.0%）,χ2_趋势检验显示:水痘疫苗效力随接种年限的延长呈逐步递减的趋势,差异有统计学意义（χ2_趋势=68.3,P<0.001）。结论 接种水痘疫苗有利于控制学校和幼儿园水痘暴发疫情;但由于水痘疫苗效力随接种年限延长逐步递减,建议实施儿童接种2剂水痘疫苗的免疫策略,从而减少学校和幼儿园的水痘暴发疫情。     

北京市昌平区高水平水痘疫苗接种率幼儿园水痘暴发调查

目的 评价水痘疫苗的保护效果,为能有效地预防接种提供依据。 方法 收集发生水痘暴发疫情幼儿园内全部儿童的水痘疫苗接种情况及发病情况,通过暴发疫情评价疫苗效果。 结果 接种水痘疫苗人群罹患率8.20%,未接种疫苗人群罹患率为34.78％,两组比较差异有统计学意义(P<0.05)。水痘疫苗保护效力为76%(95%CI:51%~91%)。接种后1年、2年、3年和3年以上的水痘疫苗保护效力分别为93%、88%、67%和43%,可见,水痘疫苗保护效力随时间推移逐步递减,并有统计学意义(趋势χ²=4.415,P<0.05)。 结论 建议对水痘疫苗免疫策略进行调整,实施儿童2剂水痘疫苗的免疫策略,建立有效的人群免疫屏障,从而减少托幼机构及小学的水痘暴发疫情。     

1起幼儿园水痘暴发调查及疫苗保护效果分析

目的 分析无锡市某幼儿园水痘暴发疫情的流行特征,评价水痘疫苗的保护效果.方法 通过病例主动搜索和问卷调查,对水痘暴发疫情进行描述性流行病学分析.采用回顾性队列研究方法评价水痘疫苗的保护效果.结果 该起暴发疫情共发生水痘病例22例,罹患率为5.39％(22/408);暴发持续31 d,波及2个班级,其罹患率分别为56.7...     

温州市一起小学水痘暴发疫情的疫苗保护效果评价

水痘是水痘—带状疱疹病毒引起的急性呼吸道传染病,具有极强的传染性,易在学校、托幼机构等集体单位暴发和流行.接种水痘疫苗是预防水痘最有效的措施,但水痘疫苗属二类疫苗,由受种者自愿自费接种.随着疫苗接种时间的延长,水痘突破病例逐渐增多[1],甚至在接种率较高的集体单位发生了暴发疫情[2-3].本文以2017年11月温州市某小学一起水痘暴发疫情流行病学调查结果为研究资料,评价水痘疫苗在该起疫情中的保护效果,为预防和控制集体单位水痘暴发疫情提供科学依据.     

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.     

宁波市学校水痘暴发疫情及疫苗接种效果调查

目的分析宁波市学校水痘暴发疫情的流行特征,评估水痘疫苗的接种效果。方法对宁波市2012—2013年学校报告的水痘暴发疫情资料进行描述性分析,调查部分学校学生免疫史并评价水痘疫苗效果。结果2012—2013年共报告学校水痘暴发疫情10起,均发生在小学,累计发病254例,罹患率为2.16%。暴发时间集中在11月,平均发病年龄为(8.55±1.81)岁。单因素分析显示,水痘疫苗对水痘发病存在统计关联(P0.05),其保护效果指数为82.37%(95%CI:60.24%~92.18%);控制年龄后,水痘疫苗亦具有保护作用,其OR值为0.13(95%CI:0.05~0.34),保护效果指数为87.25%(95%CI:66.22%~95.21%)。结论水痘暴发疫情主要发生在小学,水痘疫苗具有一定的保护作用,应提高适龄儿童水痘疫苗接种率,以控制学校暴发疫情。     

水痘疫苗接种对控制学校水痘疫情的作用分析

水痘是由水痘一带状疱疹病毒引起的儿童期常见急性呼吸道传染病,常在幼托、学校等集体单位造成暴发或流行.水痘疫苗能有效保护接种者至少5~7a[1].上海市自1999年起推荐≥1岁的学龄前儿童自费接种1剂水痘疫苗.但随着疫苗接种率的提高和接种年限的延长,水痘突破病例逐渐增多,即使在高接种率的托幼机构和小学,仍有水痘暴发疫情[2-3].     

一起学校水痘暴发疫情的流行因素及疫苗保护效果调查

目的调查一起学校水痘暴发疫情的流行病学特征,明确本起疫情发生及扩散的原因,评价水痘疫苗的保护效果。方法采用描述流行病学方法分析疫情流行病学特征,采用回顾性队列研究方法探讨疫情流行因素和水痘疫苗保护效果。结果该疫情总罹患率为5.03%(110/2 188);波及27个班4个年级,三年级和四年级罹患率较高,分别为6.48%(43/664)、5.61%(31/553);疫情历时4个月,共有7个发病高峰;在午托班午休的学生罹患率(7.01%,69/984)高于在家午休学生罹患率(4.18%,41/981),差异有统计学意义(χ~2=7.46,P=0.0063;RR=1.68,95%CI:1.16~2.44)。本次疫情中,91.82%的病例(101/110)为水痘突破病例。学生水痘疫苗总体接种率为83.09%(1 818/2 188),223名学生曾在本次疫情前罹患水痘;本次疫情发生前,水痘疫苗保护效果为75.51%(RR=0.25,95%CI:0.19~0.32),而本次疫情中,疫苗保护效果为33.50%(RR=0.67,95%CI:0.35~1.29)。结论应规范校内外午托班管理,防止疫情跨班级传播;一针次水痘疫苗在暴发疫情中保护效果较差,应进行水痘疫苗应急接种。     

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.     

Impact of vaccine cost and information about complications of varicella on parental decision regarding varicella vaccine

BACKGROUND: The influence of providing information about complications of disease and vaccine cost on parental decision to vaccinate against varicella was assessed. METHOD: During telephone interviews of 330 parents of infants aged 9 months, parents were asked if they would agree to have their child vaccinated and were presented information first about varicella complications and then about cost of the vaccine. RESULTS: When complications were explained but information about cost was not, 94% of parents were favourable toward having their child vaccinated. When complications were not explained but cost was presented, this percentage was only 34%. When both cost and complications were presented, 60% of parents were favourable toward the vaccine. INTERPRETATION: In improving receptivity towards varicella vaccine, parents should always be presented data regarding varicella complications by their health care provider.     

Universal varicella vaccine immunization in Japan

In 1974, Japanese scientists developed a live attenuated varicella vaccine based on the Oka strain. The efficacy of the vaccine for the prevention of varicella has been primarily demonstrated in studies conducted in the United States following the adoption of universal immunization using the Oka strain varicella vaccine in 1996. Although the vaccine was developed by Japanese scientists, until recently, the vaccine has been administered on a voluntary basis in Japan resulting in a vaccine coverage rate of approximately 40%. Therefore, Japan initiated universal immunization using the Oka strain varicella vaccine in November 2014. Given the transition from voluntary to universal immunization in Japan, it will also be important to monitor the epidemiology of varicella and herpes zoster.The efficacy and safety of co-administration of the varicella vaccine and measles, mumps, and rubella vaccine have been demonstrated in many countries; however, there was no data from Japan. In order to adopt the practice of universal immunization using the Oka strain varicella vaccine in Japan, data demonstrating the efficacy and safety of co-administration of varicella vaccine and measles and rubella (MR) vaccine were required. Additionally, we needed to elucidate the appropriate time interval between the first and second administrations of the vaccine. It is also important to differentiate between wild type and Oka vaccine type strains in herpes zoster patient with past history of varicella vaccine. Thus, there are many factors to consider regarding the adoption of universal immunization in Japan to control varicella zoster virus (VZV) infections.     

高疫苗覆盖率下发生水痘暴发的流行因素研究

  目的  探索1剂次水痘疫苗高覆盖率下水痘暴发的流行因素及1剂次水痘疫苗的保护效果,为控制水痘暴发疫情、调整优化水痘免疫策略提供科学依据。  方法  采用1:2配对病例对照研究,对2018年发生于江苏省苏中地区一中心小学的一起水痘暴发疫情开展流行病学调查。水痘暴发的流行因素分析采用条件Logistic逐步回归分析。  结果  该疫情共持续14 d,共报告水痘确诊病例45例,其中突破病例占71.1%。突破病例的发热情况、出疹程度、病程与无免疫史病例相比均较轻(均有P < 0.05)。条件Logistic回归分析提示,参加课外辅导机构(OR=2.6,95% CI:2.0~3.2),有兄弟姐妹(OR=2.5,95% CI:2.1~4.3),无水痘疫苗接种史(OR=2.7,95% CI:2.4~4.2),与水痘患者接触史(OR=2.4,95% CI:1.1~5.3)是水痘暴发的流行因素。接种年限>5年,初次免疫年龄 < 15月龄是发生突破病例的潜在危险因素(均有P < 0.05)。1剂次水痘疫苗的总体保护效果为77.9%(95% CI:53.3%~92.1%)。  结论  突破病例临床症状较轻,1剂次水痘疫苗不足以控制水痘暴发疫情,其疫苗保护效果有限。建议采用2剂次水痘免疫策略。     

The postmarketing safety profile of varicella vaccine

The postmarketing safety profile of varicella vaccine was evaluated by analyzing selected adverse experience reports temporally associated with the administration of the vaccine. There were 7963 reports voluntarily submitted to Merck for an overall reporting rate of 5.0 per 10000 doses of vaccine distributed. A varicella zoster virus (VZV) identification program detected the presence of the Oka vaccine strain in three individuals with an immune deficiency - two with pneumonia and one with hepatitis - and in three instances of secondary transmission from vaccinees with vesicular lesions to susceptible household contacts. The Oka vaccine strain was present in 23 patients and wild-type VZV was present in 15 patients with herpes zoster. Vesicular rashes that occurred within 2 weeks of vaccination were more likely to contain the presence of wild-type VZV, while vesicular rashes that occurred more than 2 weeks post-vaccination were more likely to contain the Oka vaccine strain. Eleven patients were hospitalized with complications of breakthrough varicella infection.     

Metaanalysis of vaccine effectiveness in varicella outbreaks

There is a number of reports on varicella outbreaks in populations where a one dose varicella immunization program has been implemented. We performed a metaanalysis to provide a summary vaccine effectiveness (VE) estimate and to assess the possible impact of waning immunity by means of a subgroup analysis by time since immunization. We found a VE of 72.5% (95% CI 68.5-76.0) derived from 3157 children in 14 publications. Immunization coverage of the respective population was unrelated to VE. All studies (n=4) that allowed the computation of VE over time since immunization showed a substantial decrease. In total, waning immunity was assessed by nine studies. Two reported no relation between VE and time since immunization without specifying how this had been assessed. Seven studies calculated relative risks for contracting varicella after prolonged as compared to a shorter period since immunization and reported an increased relative risk for prolonged periods. In conclusion, this metaanalysis confirms a limited effectiveness of one dose of varicella vaccine and points to waning immunity as an important causal factor. Waning might also be an issue with the newly recommended two dose vaccination schedule. Sustained surveillance for varicella outbreaks in populations with varicella immunization programs therefore is mandatory.     

水痘疫苗在学校水痘暴发疫情中保护效果的病例对照研究

目的 评价接种1剂水痘疫苗在学校水痘暴发疫情中的保护效果(vaccine effectiveness, VE)。方法 采用1:2配对病例对照研究,收集中山市2013—2021年水痘暴发疫情调查资料,将病例数≥5例的班的所有病例（共942例）作为病例组,按1:2的比例选取同班、同年龄（±1岁）、同性别的1 884名健康儿童作为对照组,调查其水痘疫苗接种史,采用条件logistic回归分析水痘疫苗保护效果。结果 共调查3～14岁儿童2 826名,儿童接种1剂水痘疫苗的保护效果为58%（95%CI:50%～66%）,3～5岁、6～14岁儿童接种1剂水痘疫苗保护效果分别为75%（95%CI:62%～83%）和51%（95%CI:40%～61%）。儿童接种1剂后≤2年、3～5年、6～8年、≥9年的保护效果分别为78%（95%CI:66%～86%）、66%（95%CI:57%～74%）、51%（95%CI:36%～62%）、23%（95%CI:-11%～46%）。儿童接种1剂水痘疫苗的保护效果随接种后时间的延长而降低（趋势χ²=13.071,P<0.001）。结论 儿童接种1剂水痘疫苗有助于防控水痘暴发疫情,但其保护效果随接种后时间的延长而降低,难以阻断水痘传播。建议儿童及时接种2剂水痘疫苗,以预防学校水痘暴发疫情。     

Use of a current varicella vaccine as a live polyvalent vaccine vector

Varicella-zoster virus (VZV) is the causative agent of varicella and zoster. The varicella vaccine was developed to control VZV infection in children. The currently available Oka vaccine strain is the only live varicella vaccine approved by the World Health Organization. We previously cloned the complete genome of the Oka vaccine strain into a bacterial artificial chromosome vector and then successfully reconstituted the virus. We then used this system to generate a recombinant Oka vaccine virus expressing mumps virus gene(s). The new recombinant vaccine may be an effective polyvalent live vaccine that provides protection against both varicella and mumps viruses. In this review, we discussed about possibility of polyvalent live vaccine(s) using varicella vaccine based on our recent studies.     

水痘减毒活疫苗保护效果的配对病例对照研究

了解水痘疫苗保护效果及疫苗保护效果随时间推移的衰减情况,为适时开展加强接种提供依据.方法 采用1∶1配对病例对照研究方法,对绍兴市越城区2012年337例2~12岁水痘病例进行调查分析.结果 病例组水痘疫苗接种率(24.03%)低于对照组(67.06%),差异有统计学意义(x2=122.202,P<0.01).1剂水痘疫苗接种后保护率为84.62%(95%CI为77.99% ~ 89.25%);水痘疫苗保护率随时间推移而逐步递减(x2=17.878,P<0.0l).结论 接种水痘疫苗是预防水痘的有效措施,但随时间推移,保护效果呈逐步递减趋势.建议适时开展加强接种.     

Current status and prospects of live varicella vaccine

Since its development in 1974 the Oka strain live attenuated varicella vaccine has been tested in healthy and immunocompromised adults and children. Its safety and efficacy have been established and it is now licensed for general use in Japan and Korea, and for immunocompromised patients in several other countries. Possibilities for the future include its use to prevent zoster in the elderly, its incorporation in a multivalent vaccine and its use as a vehicle to express foreign genes in recombinant vaccines.     

Development of varicella vaccine in Japan and future prospects

In Japan, Dr. Michiaki Takahashi (1928–2013) successfully developed the first live attenuated varicella vaccine in the world. The virus used for this vaccine was varicella-zoster virus isolated from the vesicular fluid of a child with typical varicella and it was named the Oka strain after the family name of the child. In 1974, a patient with nephrosis developed varicella in the Pediatric Ward, and uninfected pediatric patients received varicella vaccine immediately. As a result, there were no cases of varicella in the other children and all of the vaccinated children acquired immunity to the disease. These results were published in the Lancet, demonstrating the safety and efficacy of varicella Oka strain vaccine for the first time. When clinical studies were conducted at the start of vaccine development, most of the subjects were pediatric patients with a high risk of contracting severe varicella. Therefore, the development process was different from that for other vaccines, since clinical studies are generally performed in healthy individuals.This vaccine was approved in Japan in 1986, and voluntary single-dose vaccination for children aged 1 year or older was started in 1987. However, the vaccination coverage rate remained low and the number of patients with varicella did not decrease significantly. Due to its voluntary status, the cost of vaccination was borne by the child's family and this was considered to be a reason for the low coverage rate. Moreover, although the vaccine achieved a good antibody response, the number of cases of breakthrough varicella (BV) was relatively high and showed an increasing trend that was also a concern. In order to increase the coverage rate and reduce BV, the Japanese government changed the varicella vaccination policy from voluntary to routine vaccination in October 2014. At the same time, a two-dose schedule was introduced that involved administration of the vaccine twice at an interval of at least 3 months up to the age of 3 years.At present, cases of varicella are only monitored at the pediatric sentinel clinics in Japan. Therefore, we need to establish a system to survey all patients, in order to demonstrate the efficacy of varicella vaccine based on detailed surveillance data. We also need to investigate the optimum timing of the second dose of the vaccine and the necessity for further booster vaccination. A combined live vaccine containing varicella vaccine has not yet been approved in Japan. Because of the greater convenience of combined vaccines, development and introduction of such a vaccine in the future would be desirable. Routine varicella vaccination is also expected to eventually reduce the occurrence of herpes zoster, although there are no supporting epidemiological data. The prevalence of herpes zoster has attracted attention, but it is necessary to develop a surveillance system for this disease. In March 2016, use of varicella vaccine to prevent herpes zoster in adults aged 50 years or older was approved in Japan, and the results of this policy change need to be assessed.