新型冠状病毒疫苗接种策略经济学评价研究进展

目的了解国内外新型冠状病毒疫苗(新冠疫苗)接种策略相关的经济学评价研究进展, 为开展基于中国真实世界证据疫苗接种策略经济学评价提供参考。方法对中英文数据库2020年1月至2021年12月的文献进行检索, 纳入新冠疫苗接种策略经济学评价研究, 并对相关文献进行叙述性整合。结果共纳入16篇英文文献(含3篇综述), 发现无论品种, 接种新冠疫苗都具有成本效果或节省成本, 但不同人群和剂次接种策略的成本效果由于受疫苗有效率、价格、自然免疫持续时间、接种策略持续时长、供应情况、接种速度的影响而不同。结论国内缺少长期疫情流行趋势下基于中国真实世界证据的新冠疫苗接种策略经济学评价证据, 对于疫苗加强针接种的合理策略仍需进一步研究。     

整群随机设计在疫苗临床试验中的应用

当疫苗在人群中的覆盖率达到一定比例时，群体保护效果将保护未接种疫苗者。但传统疫苗临床评价采用的个体随机设计无法评估疫苗的群体保护效果。相较于个体随机设计，整群随机设计可以更全面地评估疫苗的总体保护效应。近年来，在疫苗临床的Ⅲ、Ⅳ期临床试验中，整群随机设计变得更加常见。但目前国内对整群随机设计在疫苗临床试验中的应用了解较少。因此，本文对整群随机设计在疫苗临床试验中的应用进行综述，为今后我国开展相关方面的研究提供参考。     

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。     

老年人群肺炎疫苗接种的影响因素分析

目的研究影响老年人接种肺炎疫苗的因素．提出促进老年人疫苗接种的策略和政策性建议。方法对与老年人接种肺炎疫苗的相关人群包括医务人员、街道市政科工作人员及预防接种门诊工作人员进行一对一深入访谈。结果除预防接种门诊工作人员外，其余相关人群对肺炎疫苗认知度低，影响肺炎疫苗接种的主要原因是宣传力度不够和疫苗价格太贵。结论加强有针对性的宣传对促进肺炎疫苗的接种具有重要作用。降低价格、纳入医保对肺炎疫苗的接种也具有促进作用。     

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。     

基于倾向得分匹配的老年人接种流感疫苗对流感就诊的保护效果研究

目的 评估老年人接种流感疫苗对流感就诊的保护效果,并探讨倾向得分匹配法（PSM）在疫苗保护效果研究中的应用价值。方法 以成都市为研究现场,选取2017年9-12月间接种流感疫苗的60岁及以上老年人作为接种组,采用PSM法选取观察对象作为对照组。匹配后比较两组人群疫苗接种后一年内的流感就诊情况,评价疫苗保护效果。结果 流感疫苗接种组与未接种组各有1442例匹配成功。两组的一般人口学特征、生活方式及健康意识、基本健康状况等特征在匹配前有显著差异,匹配后两组协变量达到均衡。匹配后接种组和对照组流感就诊率分别为0.69%、2.84%,疫苗接种可减少之后一年内75.70%的流感就诊。结论 PSM可有效降低观察性研究组间的混杂偏倚,在疫苗接种效果评价中具有长远的应用价值。流感疫苗接种对降低≥60岁老年人流感就诊具有良好效果,今后有必要采取措施提高流感疫苗接种率。     

预防接种人群对乙型病毒性肝炎防治及疫苗接种知识的认知调查

目的:分析预防接种人群对乙型病毒性肝炎防治及疫苗接种知识的认知调查。方法:随机选择我院2017年4月至2018年4月门诊预防接种乙肝疫苗者450名,通过了解接种疫苗者背景,分为已接种疫苗和未接种疫苗两组,分别发放自行设计问卷调查。结果:经调查,已接种疫苗者在乙肝防治、疫苗接种相关知识的知晓率明显高于未接种疫苗者(P0.05),而大专及以上,年龄19-29岁之间的接种者,其接种率明显高于其它学历及年龄人群(P0.05)。结论:我国人群对乙肝防治及疫苗接种知识仍然偏低,医院应利用接种疫苗的机会对活动人群开展教育宣讲工作,提高易感染人群疫苗接种率。     

我国男男性行为人群中人乳头瘤病毒疫苗接种的需求与建议

MSM是HPV感染与相关疾病发生的高危人群,四价和九价HPV疫苗能够为MSM提供有效的保护。本文综述了为MSM提供HPV疫苗接种的重要性,综合了关于MSM接种HPV疫苗的依据并提出建议:我国应加快HPV疫苗在男性中使用的适应症研究及审批;尽快为HIV阳性的MSM接种HPV疫苗;优先为 ≤ 26岁MSM接种HPV疫苗;在HPV疫苗资源充分的情况下,为>26岁的MSM进行补接种或机会性接种。采用这种接种策略能够为MSM提供保护,控制性病和艾滋病的传播。     

2009年上海市中小学生甲型H1N1流感疫苗大规模接种流行病学效果评价

目的 评价2009年上海市中小学生接种甲型H1N1流行性感冒疫苗(简称甲流疫苗)的流行病学效果.方法 研究对象为长宁、杨浦、闸北、普陀、浦东新区和崇明县内接受甲流疫苗接种(接种组)和未接受甲流疫苗接种(对照组)的在校中小学生,分别收集接种组与对照组学生每日的发热和流感样病例数,通过计算疫苗保护率和保护效果指数,以评价甲流疫苗的流行病学效果.结果 甲流疫苗接种前,流感样病例的发病高峰是在2009年11月,流感样病例罹患率达6.19%.接种疫苗后,接种组发热的罹患率为0.98%,流感样病例的罹患率为0.61%;对照组发热的罹患率为2.37%,流感样病例的罹患率为1.75%.与对照组相比,接种组甲流疫苗接种后控制发热的保护率为58.65%,保护效果指数为2.42,控制流感样病例的保护率为65.14%,保护效果指数为2.87.结论 接种甲流疫苗可以降低中小学生发热及流感样病例的发生率,具有一定的保护作用.     

乙型肝炎疫苗免疫人群效果观察

为评价乙型肝炎 (乙肝 )疫苗在人群中应用的效果 ,采用多阶段整群系统随机抽样的方法 ,对河南省 13个县市中的 1890个家庭 ,5890人进行乙肝疫苗接种情况的调查。发现接种疫苗者HBsAg阳性率明显降低 ,抗 HBs阳性率明显升高。只接种 1针者无免疫保护作用 ;2岁内接种疫苗效果最好 ;5岁以下儿童中接种率达到 70 %时可使HBsAg阳性率降低到 1%以下。结果说明乙肝疫苗在人群中应用效果明显 ,小年龄接种和全程接种对效果影响显著 ,维持高的接种率才会使相应人群带毒率明显下降。     

Estimation of the herd protection of Haemophilus influenzae type b conjugate vaccine against radiologically confirmed pneumonia in children under 2 years old in Dhaka,Bangladesh

Background Herd protection of Haemophilus influenzae type b (Hib) conjugate vaccine has been associated with excessive decrease of invasive Hib diseases, i.e., pneumonia and meningitis, with increased national or regional Hib vaccine coverage. Only a few studies have examined herd protection at the individual level and even less evidence is available from Asia. We examined Hib vaccine herd protection against radiologically confirmed pneumonia among children less than 2 years old.     

Establishing herd immunity against Ebola through vaccination

ObjectivesIn response to recent concern regarding Ebola outbreaks, this study aims to (1) determine the relationship between vaccination coverage and herd immunity, (2) determine the vaccination coverage necessary to establish herd immunity for previous Ebola viruses, and (3) recommend vaccination coverage thresholds for future Ebola viruses.MethodsHerd immunity thresholds needed to block transmission of Ebola virus were determined using vaccine efficacy and number of secondary cases per infected case during an entire infectious period.ResultsIn past Ebola outbreaks 42.2–63.0% of the population would need to be vaccinated in order to prevent transmission and outbreaks. Assuming 80% vaccine efficacy as reported by phase I clinical trials, 52.7–78.7% of the population would require vaccination coverage in order to establish herd immunity. In recent ring vaccination trials which considered the vaccine to be 100% effective after 10 days, 42.2–63.0% of the population would need to be vaccinated.ConclusionFor future Ebola outbreaks, the spread of the virus can be prevented by vaccinating certain percentages of the population depending on vaccine efficacy and number of secondary cases per infected case.     

‘What have you HEARD about the HERD?’ Does education about local influenza vaccination coverage and herd immunity affect willingness to vaccinate?

BackgroundVaccination protects individuals directly and communities indirectly by reducing transmission. We aimed to determine whether information about herd immunity and local vaccination coverage could change an individual’s vaccination plans and concern about influenza.MethodsWe surveyed Minnesota residents ≥18 years during the 2016 Minnesota State Fair. Participants were asked to identify the definition of herd immunity, to report their history of and plans to receive influenza vaccine, to report their concern about influenza, and to estimate the reported influenza vaccination coverage in their county. After providing educational information about herd immunity and local vaccination rates, we reassessed vaccination plans and concerns. We used logistic regression to estimate predicted percentages for those willing to be vaccinated, for concern about influenza, and for changes in these outcomes after the intervention. We then compared those individuals with and without prior knowledge of herd immunity, accounting for other characteristics.ResultsAmong 554 participants, the median age was 57 years; most were female (65.9%), white (91.0%), and non-Hispanic/Latino (93.9%). Overall, 37.2% of participants did not know about herd immunity and 75.6% thought that the influenza vaccination coverage in their county was higher than it was reported. Those not knowledgeable about herd immunity were significantly less likely than those knowledgeable about the concept to report plans to be vaccinated at baseline (67.8% versus 78.9%; p = 0.004). After learning about herd immunity and influenza vaccination coverage, the proportion of those not knowledgeable about herd immunity who were willing to be vaccinated increased significantly by 7.3 percentage points (p = 0.001). Educating participants eliminated the significant difference in the proportion planning to be vaccinated between these two groups (80.1% of those knowledgeable and 75.1% of those who were not initially knowledgeable became willing; p = 0.148).ConclusionsEducation about herd immunity and local vaccination coverage could be a useful tool for increasing willingness to vaccinate, generating benefits both to individuals and communities.     

Measuring indirect effects of rotavirus vaccine in low income countries

Widespread introduction of rotavirus vaccines has led to major reductions in the burden of rotavirus gastroenteritis worldwide. Vaccine effectiveness is diminished, however, in low income countries, that harbour the greatest burden of rotavirus attributed morbidity and mortality. Indirect effects of rotavirus vaccine (herd immunity and herd protection) could increase population level impact and improve vaccine cost effectiveness in such settings. While rotavirus vaccine indirect effects have been demonstrated in high and middle income countries, there are very little data from low income countries where force of infection, population structures and vaccine schedules differ. Targeted efforts to evaluate indirect effects of rotavirus vaccine in low income countries are required to understand the total impact of rotavirus vaccine on the global burden of rotavirus disease.     

Re-evaluation of population-level protection conferred by a rotavirus vaccine using the ‘fried-egg’ approach in a rural setting in Bangladesh

BackgroundVaccine herd protection assessed in a cluster-randomized trial (CRT) may be masked by disease transmission into the cluster from outside. However, herd effects can be unmasked using a ‘fried-egg’ approach whereby the analysis, restricted to the innermost households of clusters, ‘yolk’, creates an insulating ‘egg-white’ periphery. This approach has been demonstrated to unmask vaccine herd protection in reanalyses of cholera and typhoid vaccine CRTs. We applied this approach to an earlier CRT in Bangladesh of rotavirus vaccine (RV) whose overall analysis had failed to detect herd protection. Herein we present the results of this analysis.MethodsIn the study area, infants in 142 villages were randomized to receive two doses of RV with routine EPI vaccines (RV villages) or only EPI vaccines (non-RV villages). We analyzed RV protection against acute rotavirus diarrhoea for the entire cluster (P100) and P75, P50, P25 clusters, representing 75%, 50% and 25% of the innermost households for each cluster, respectively.ResultsDuring 2 years of follow-up, there was evidence of 27% overall (95 %CI: 7, 43) and 42% total protection (95 %CI: 23, 56) in the P100 cluster, but it did not increase when moved in smaller yolks. There was no evidence of indirect vaccine protection in the yolks at any cluster size.ConclusionOur reanalysis of the CRT using the fried- egg approach did not detect RV herd protection. Whether these findings reflect a true inability of the RV to confer herd protection in this setting, or are due to limitations of the approach, requires further study.     

The vaccination coverage required to establish herd immunity against influenza viruses

Objective

1) To determine the influenza vaccination coverage required to establish herd immunity, and 2) to assess whether the percentages of vaccination coverage proposed and those registered in the United States and Europe are sufficient to establish herd immunity.

Methods

The vaccination coverage required to establish herd immunity was determined by taking into account the number of secondary cases per infected case (R_o) and the vaccine effectiveness.

Results

The required percentage that would have been required to establish herd immunity against previous influenza viruses ranged from 13% to 100% for the 1918-19, 1957-58, 1968-69 and 2009-10 pandemic viruses, and from 30% to 40% for the 2008-09 epidemic virus. The objectives of vaccination coverage proposed in the United States — 80% in healthy persons and 90% in high-risk persons — are sufficient to establish herd immunity, while those proposed in Europe — only 75% in elderly and high-risk persons — are not sufficient. The percentages of vaccination coverage registered in the United States and Europe are not sufficient to establish herd immunity.

Conclusion

The influenza vaccination coverage must be increased in the United States and Europe in order to establish herd immunity. It is necessary to develop new influenza prevention messages based on herd immunity.     

Trends in school-level vaccination coverage from 2015 to 2018: Increases in exemption rates and declines in herd immunity in Arizona

Vaccination enrollment requirements are an important tool used to improve vaccination coverage among school-aged children. However, all states permit varying exemptions that allow students to stay enrolled without receiving some (or all) vaccinations. In Arizona, schools are required to report vaccination data on their kindergarten and 6th grade students annually to the Arizona Department of Health Services (ADHS). We analyzed trends in herd immunity and personal belief exemptions in Arizona schools from 2015 to 2018. We also identified multiple correlates of herd immunity at the school level. Our results demonstrate decreased herd immunity statewide and by school type and an increased rate of personal belief exemptions during this period. These findings contribute to the body of literature suggesting that vaccine hesitancy is growing, resulting in suboptimal vaccination coverage for children. Moreover, this research has several policy implications, especially for states permitting multiple exemption types and lax exemption criteria.     

Impact of rotavirus vaccination on epidemiological dynamics in England and Wales

Rotavirus infection causes severe gastroenteritis (RVGE) in children worldwide. Its disease burden has been reduced in countries where mass vaccination programs have been introduced. However, England and Wales have not yet implemented such a mass vaccination program. This paper uses a dynamic model to predict the effect of a mass vaccination program in England and Wales beginning in the fall of 2011. The dynamic model is parameterized with country-specific data for the introduction of a rotavirus vaccine. We report the impact of vaccination, in both the short- and long-term, on disease incidence reduction, timing of seasonal epidemics and the level of herd protection. Our results predict that vaccination can reduce the burden of severe RVGE by 70% and delay the rotavirus epidemic peak by two and a half months with a coverage of 95%. Our calculations further show that herd protection accounts for about a quarter of the reduction in RVGE incidence. If vaccine-induced protection does not wane over three years, severe RVGE in children under five years of age could be eliminated within two years after the introduction of vaccination. This work lays the foundation for policy-makers to determine the impact of a mass vaccination program against rotavirus in England and Wales.     

Vaccine impact: Benefits for human health

Unlike most drugs, whose benefit is restricted to the individual who takes the drug, prophylactic vaccines have the potential for far-reaching effects that encompass health service utilisation, general health and wellbeing, cognitive development and, ultimately, economic productivity. The impact of immunisation is measured by evaluating effects directly on the vaccinated individual, indirectly on the unvaccinated community (herd protection), the epidemiology of the pathogen (such as changing circulating serotypes or prevention of epidemic cycles), and the additional benefits arising from improved health. Aside from protection of the individual, the broader success of immunisation is dependent on achieving a level of coverage sufficient to interrupt transmission of the pathogen. When evaluating the cost-effectiveness of vaccines, all of these potential benefits need to be accounted for. In many countries where immunisation programmes have been highly successful, the control of disease has meant that the benefits of immunisation have become less obvious. Once a well-known and much-feared disease appears to have disappeared, individuals, including healthcare professionals, no longer view ongoing prevention with the same sense of urgency. Reduced coverage is inevitably associated with resurgence in disease, with outbreaks potentially leading to significant morbidity and loss of life. Ensuring the continued success of immunisation programmes is the responsibility of all: individuals, healthcare professionals, government and industry.     

Cost-Effectiveness of New-Generation Oral Cholera Vaccines: A Multisite Analysis

Objectives:  We evaluated the cost-effectiveness of a low-cost cholera vaccine licensed and used in Vietnam, using recently collected data from four developing countries where cholera is endemic. Our analysis incorporated new findings on vaccine herd protective effects.
Methods:  Using data from Matlab, Bangladesh, Kolkata, India, North Jakarta, Indonesia, and Beira, Mozambique, we calculated the net public cost per disability-adjusted life year avoided for three immunization strategies: 1) school-based vaccination of children 5 to 14 years of age; 2) school-based vaccination of school children plus use of the schools to vaccinate children aged 1 to 4 years; and 3) community-based vaccination of persons aged 1 year and older.
Results:  We determined cost-effectiveness when vaccine herd protection was or was not considered, and compared this with commonly accepted cutoffs of gross domestic product (GDP) per person to classify interventions as cost-effective or very-cost effective. Without including herd protective effects, deployment of this vaccine would be cost-effective only in school-based programs in Kolkata and Beira. In contrast, after considering vaccine herd protection, all three programs were judged very cost-effective in Kolkata and Beira. Because these cost-effectiveness calculations include herd protection, the results are dependent on assumed vaccination coverage rates.
Conclusions:  Ignoring the indirect effects of cholera vaccination has led to underestimation of the cost-effectiveness of vaccination programs with oral cholera vaccines. Once these effects are included, use of the oral killed whole cell vaccine in programs to control endemic cholera meets the per capita GDP criterion in several developing country settings.