Revaccination of children during school-based measles outbreaks: potential impact of a new policy recommendation.

OBJECTIVE: To evaluate the potential impact of revaccination on measles outbreak control during school-based epidemics. DESIGN: Retrospective cohort study. SETTING: Thirty-two public elementary and high schools in 14 communities on the west island of Montreal. PARTICIPANTS: All 19,439 children attending these schools during the 1989 measles epidemic in Quebec. INTERVENTION: After notification of a case children with provider-verified records of vaccination on or after their first birthday were identified; the remaining children were vaccinated or excluded from school. OUTCOME MEASURE: Clinical or confirmed measles cases not prevented by this intervention that could have been prevented had revaccination been included during the outbreak. RESULTS: Of the 88 measles cases (74 confirmed) proof of one adequate vaccination was present in 48 (55%). Intervention generally occurred within 5 school days after case notification. The nonpreventable cases involved 75 children who had measles onset before the intervention and 11 (7 vaccinated) who had onset within 8 days after the intervention. The two remaining cases occurred 20 and 25 days after the intervention among nonvaccinated students who refused to be vaccinated. Except for these two cases measles was eliminated at every school. Application of the new Canadian guidelines for measles outbreak control would have required the administration of at least 10,000 additional doses during the outbreak to students vaccinated before 1980; implementation of the new US guidelines would have required the administration of 16,629 additional doses to children previously vaccinated only once. Well-enforced provincial regulations ensuring vaccination of every student upon school entry might have prevented 38 (43%) of the cases. The US recommendation of two routine doses of vaccine before school entry might have prevented 86 (98%) of the cases. However, revaccination during the outbreak would not have prevented a single additional case. CONCLUSION: Revaccination of previously vaccinated students during a measles outbreak would have been costly and of little benefit.     

郑州市麻疹疫苗强化免疫前后麻疹流行病学特征分析

目的了解郑州市麻疹疫苗强化免疫对疾病流行特征的影响,为消除麻疹采取针对性措施提供科学依据。方法对郑州市麻疹强化免疫活动前后的2010年和2011年麻疹发病情况进行描述性流行病学分析。结果郑州市强化免疫后麻疹病例大幅减少,2011年较2010年病例数减少90%;全年病例散发,无明显季节性高峰出现;病例构成仍以1岁以下儿童和无免疫史者为主;城区发病高于农村。结论此次麻疹强化免疫活动效果明显,致使麻疹发病率显著下降。     

Seasonal transmission dynamics of measles in China

Measles, a highly contagious infection caused by the measles virus, is a major public health problem in China. The reported measles cases decreased dramatically from 2004 to 2012 due to the mandatory measles vaccine program started in 2005 and the goal of eliminating measles by 2012. However, after reaching its lowest level in 2012, measles has resurged again since 2013. Since the monthly data of measles cases exhibit a seasonally fluctuating pattern, based on the measles model in Earn et al. (Science 287:667–670, 2000), we propose a susceptible, exposed, infectious, and recovered model with periodic transmission rate to investigate the seasonal measles epidemics and the effect of vaccination. We calculate the basic reproduction number \({\mathcal {R}}_{0}\), analyze the dynamical behavior of the model, and use the model to simulate the monthly data of measles cases reported in China. We also carry out some sensitivity analysis of \({\mathcal {R}}_{0}\) in the terms of various model parameters which shows that measles can be controlled and eventually eradicated by increasing the immunization rate, improving the effective vaccine management, and enhancing the awareness of people about measles.     

Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis

ObjectiveTo estimate changes in the risk of autism and assess the relation of autism to the mumps, measles, and rubella (MMR) vaccine. DesignTime trend analysis of data from the UK general practice research database (GPRD).SettingGeneral practices in the United Kingdom.SubjectsChildren aged 12 years or younger diagnosed with autism 1988-99, with further analysis of boys aged 2 to 5 years born 1988-93.ResultsThe incidence of newly diagnosed autism increased sevenfold, from 0.3 per 10 000 person years in 1988 to 2.1 per 10 000 person years in 1999. The peak incidence was among 3 and 4 year olds, and 83% (254/305) of cases were boys. In an annual birth cohort analysis of 114 boys born in 1988-93, the risk of autism in 2 to 5 year old boys increased nearly fourfold over time, from 8 (95% confidence interval 4 to 14) per 10 000 for boys born in 1988 to 29 (20 to 43) per 10 000 for boys born in 1993. For the same annual birth cohorts the prevalence of MMR vaccination was over 95%.ConclusionsBecause the incidence of autism among 2 to 5 year olds increased markedly among boys born in each year separately from 1988 to 1993 while MMR vaccine coverage was over 95% for successive annual birth cohorts, the data provide evidence that no correlation exists between the prevalence of MMR vaccination and the rapid increase in the risk of autism over time. The explanation for the marked increase in risk of the diagnosis of autism in the past decade remains uncertain.     

Subacute sclerosing panencephalitis in papua new guinean children: the cost of continuing inadequate measles vaccine coverage

Introduction

Subacute sclerosing panencephalitis (SSPE) is a late, rare and usually fatal complication of measles infection. Although a very high incidence of SSPE in Papua New Guinea (PNG) was first recognized 20 years ago, estimated measles vaccine coverage has remained at ≤70% since and a large measles epidemic occurred in 2002. We report a series of 22 SSPE cases presenting between November 2007 and July 2009 in Madang Province, PNG, including localized clusters with the highest ever reported annual incidence.

Methodology/Principal Findings

As part of a prospective observational study of severe childhood illness at Modilon Hospital, the provincial referral center, children presenting with evidence of meningo-encephalitis were assessed in detail including lumbar puncture in most cases. A diagnosis of SSPE was based on clinical features and presence of measles-specific IgG in cerebrospinal fluid and/or plasma. The estimated annual SSPE incidence in Madang province was 54/million population aged <20 years, but four sub-districts had an incidence >100/million/year. The distribution of year of birth of the 22 children with SSPE closely matched the reported annual measles incidence in PNG, including a peak in 2002.

Conclusions/Significance

SSPE follows measles infections in very young PNG children. Because PNG children have known low seroconversion rates to the first measles vaccine given at 6 months of age, efforts such as supplementary measles immunisation programs should continue in order to reduce the pool of non-immune people surrounding the youngest and most vulnerable members of PNG communities.     

Analysis of a measles epidemic; possible role of vaccine failures.

A measles epidemic occurred in the Greensville (Ont.) Unit schools during January and February 1975. There were 47 cases of measles in 403 students: 26 (55%) of the children had a history of being vaccinated and 18 (38%) had not been vaccinated. Among children known to have been vaccinated at less than 1 year of age 7 of 13 contracted measles, while among the 48 children who had not been vaccinated 18 contracted measles. The attack rate among vaccinees increased with increasing time since vaccination. The observations of this study as well as those of similar studies suggest that vaccine failures contributed to the genesis of the epidemic. It is recommended that all children initially vaccinated at less than 1 year of age should be revaccinated with live attenuated measles virus vaccine.     

Increase in congenital rubella occurrence after immunisation in Greece: retrospective survey and systematic review

ObjectiveTo describe the events leading to the epidemic of congenital rubella syndrome in Greece in 1993 after a major rubella epidemic.DesignRetrospective survey and systematic review.SettingGreece (population 10 million), 1950-95.SubjectsChildren, adolescents, and women of childbearing age.ResultsAround 1975 in Greece the measles, mumps, and rubella vaccine started being given to boys and girls aged 1 year without policies to attain high vaccination coverage and to protect adolescents and young women. During the 1980s, vaccination coverage for rubella remained consistently below 50%, and the proportion of pregnant women susceptible to rubella gradually increased. In 1993 the incidence of rubella in young adults was higher than in any previous epidemic year. The epidemic of congenital rubella that followed, with 25 serologically confirmed cases (24.6 per 100 000 live births), was probably the largest such epidemic in Greece after 1950.ConclusionsWith low vaccination coverage, the immunisation of boys and girls aged 1 year against rubella carries the theoretical risk of increasing the occurrence of congenital rubella. This phenomenon, which has not been previously reported, occurred in Greece.     

许昌市2009—2013年麻疹流行病学特征和监测系统运转状况分析

目的分析许昌市2009—2013年麻疹流行特征和监测系统运转状况,为加速消除麻疹制定策略及措施提供科学依据。方法利用描述性流行病学方法对许昌市2009—2013年麻疹监测系统资料进行统计分析。结果许昌市2009—2013年累计报告麻疹病例675例,年均报告发病率为3.16/10万。全市8个县、市区均有病例报告,病例数主要集中在禹州市,占总病例数的55.56%;发病呈明显的季节性分布,主要集中在2—5月份,占总病例数的73.48%;病例主要集中于0~6岁儿童,占总病例数的85.63%,其中1岁以下婴幼儿占总病例数的50.22%;8月龄~14岁麻疹病例中有确切免疫史者仅占38.58%。随着监测系统及时性和特异性逐年提高,48 h完整调查率由2009年的88.32%上升至2012年的100%;血标本3 d内送达率由2009年的51.68%上升至2013年的100%;实验室结果 7 d内报告率由2009年的52.80%上升至2013年的100%;血标本采集率从2009年48.86%上升至2013年的100%;暴发血清学确诊率、病原学标本采集率均上升至100%。2009—2013年麻疹监测系统敏感性低,排除病例报告发病率为0.49/10万~1.43/10万。结论 2009—2013年许昌市麻疹发病率下降,小年龄组发病构成增加。监测系统运转综合质量逐年提升,但敏感性低。今后应进一步加强麻疹类疫苗接种与管理,提高人群免疫水平;加强医疗机构传染病报告与管理,提高监测系统敏感性,防止传染源扩散。     

佛山市南海区2004—2010年麻疹流行病学特征分析及控制策略探讨

了解佛山市南海区2004—2010年麻疹流行病学特征,为进一步完善和制订消除麻疹策略与措施提供科学依据。采用流行病学方法对佛山市南海区2004—2010年麻疹发病资料进行分析。结果显示,佛山市南海区2004—2010年累计确诊麻疹病例1 376例,年平均发病率为9.24/10万;全年均有发病,3～8月是麻疹高发季节,但近年来随着麻疹防控措施的落实,季节性已不明显;麻疹发病以5岁以下儿童为主,占总发病数的55.7%,,近年来麻疹发病年龄趋势向<1岁人群组和≥15岁人群组发展,这两个年龄组发病数占总发病人数的62.8%;病例中无免疫史或免疫史不详者占92.2%。佛山市南海区麻疹发病年龄分布已逐步呈现"双向位移"现象,加强对重点人群、重点地区的免疫规划管理,提高麻疹疫苗接种率,是控制麻疹发病的有效措施。同时适时开展强化免疫接种是保护易感人群,进而实现消除麻疹的重要策略.     

Evidence of recombination among early-vaccination era measles virus strains

Background  

The advent of live-attenuated vaccines against measles virus during the 1960'ies changed the circulation dynamics of the virus. Earlier the virus was indigenous to countries worldwide, but now it is mediated by a limited number of evolutionary lineages causing sporadic outbreaks/epidemics of measles or circulating in geographically restricted endemic areas of Africa, Asia and Europe. We expect that the evolutionary dynamics of measles virus has changed from a situation where a variety of genomic variants co-circulates in an epidemic with relatively high probabilities of co-infection of the individual to a situation where a co-infection with strains from evolutionary different lineages is unlikely.     

104例麻疹病例的流行病学分析

目的分析平顶山市麻疹病例发生的原因,为加速控制和消除麻疹提供科学依据。方法对平顶山市2013年法定传染病疫情报告资料和麻疹监测资料进行流行病学分析。结果平顶山市2013年共报告麻疹104例,年发病率为2.11/10万,2~4月为发病高峰;男女发病率差异有统计学意义,发病以3岁以下儿童居多,占发病总数的86.54%;其中8月龄~1岁者最多,占39.42%;14岁以上者9例,占8.65%,其他年龄组发病率随年龄增大而逐步下降。从病例就诊、住院时间上推断其感染方式可能以医院内感染为主。结论常规免疫接种率和首针及时接种率不高是麻疹高发的主要原因,医院内交叉感染是麻疹的传播因素,提高易感人群麻疹疫苗接种率,控制院内感染是控制、消除麻疹的有效手段。     

Molecular epidemiology of measles virus

Genetic analysis of viruses associated with recent outbreaks of measles in the United States indicated that at least four genotypes were present during 1994 and 1995. None of these more recent genotypes were related to the genotype responsible for the resurgence of measles cases in the United States between 1989 and 1992. The sequence data confirmed that the majority of measles cases that occurred in the United States between 1994 and 1995 were the result of international importation of virus. The data also suggested that transmission of the genotype associated with the resurgence had been interrupted by aggressive control measures. Therefore, molecular epidemiologic studies will provide a powerful means to measure the success of measles control strategies.     

佛山市2004—2009年麻疹流行病学分析和防治措施探讨

通过分析近年来佛山市麻疹流行病学特征,为探讨麻疹控制措施提供理论依据。对2004—2009年麻疹发病情况进行描述性流行病学分析。结果显示,佛山市2004—2009年共报告麻疹病例3 599例,年平均发病率为10.19/10万;发病数前3位的区为顺德区、南海区、禅城区,占全市病例数的94.50%;4～8月为高发季节,占总病例数的66.60%;6岁以下儿童及15岁以上人群是麻疹发病主要人群,分别占总病例数的62.86%、31.54%;8月龄以下儿童发病数占14.48%;病例以流动人口为主,占总病例数的94.78%;有明确免疫史病例仅占总病例数10.22%。佛山市麻疹发病有回升趋势,疫情形势严峻。实施麻疹疫苗强化免疫和查漏补种是控制麻疹的有效措施;同时应采取加强流动人口管理,提高麻疹疫苗常规免疫接种率和及时率,加强麻疹监测和入学、入托查验证管理,控制医院内感染,强化疫区处理等综合防控措施。     

许昌市2010年麻疹疫情分析

研究许昌市麻疹流行特征,为消除麻疹提供科学依据.对许昌市2010年麻疹疫情进行描述流行病学分析.结果显示2010年全市共报告麻疹确诊病例158例,报告发病率为3.74/10万;流行毒株为麻疹病毒H1a基因型.3-5月份是发病高峰;0～3岁龄儿童为主,其中小于8月龄病例占报告发病数的32.91％;8- 17月龄病例,68...     

深圳市南山区西丽人民医院辖区2005-2009年麻疹疫情分析

为了掌握深圳市南山区西丽人民医院辖区内麻疹病毒流行现状,评价该院辖区麻疹疫苗接种效果,为今后制订麻疹预防控制策略提供依据。采用回顾性调查方法,将2005-2009年间的麻疹发病情况作了分析。2005、2007两年发病人数最多,发病率较高,随着麻疹疫苗强化免疫活动的开展,使疫情有了较大的下降趋势。结果表明,接种麻疹疫苗是最有效地预防麻疹疫情的手段。     

青海省15岁以下儿童麻疹疫苗强化免疫分析

实验中对麻疹疫苗强化免疫前、后的现场进行了调查、评估并对麻疹监测系统和传染病报告系统的疫情资料进行了分析。结果表明,这次强化免疫接种儿童1100315人,报告接种率和调查接种率均>95%;接种后麻疹发病人数明显减少,发病率仅为0.66/10万,较强化免疫前发病率9.15/10万下降了82.51%,约有1/3不良反应者确诊为风疹;2006年7月—2007年6月麻疹监测系统数据显示,目前88%的麻疹病例发生在8月龄~14岁,约有32%病例为无免疫史或免疫史不详。高质量MV强化免疫能迅速降低麻疹发病,因此强化免疫接种人群的确定必须结合当地流行病学监测资料并尽可能在较大范围内开展,以形成有效的人群免疫屏障来阻断麻疹病毒的传播。保证>95%接种率是该次强化免疫活动的前提,同时须作好充分准备以应对可能发生预防接种时出现的不良反应。建议在提高常规免疫服务质量的情况下,每3~4年仍需开展后续强化免疫。     

Recurring measles epidemic in Vietnam 2005-2009: implication for strengthened control strategies

Background: Measles remains a serious vaccine preventable cause of mortality in developing nations. Vietnam is aiming to achieve the level of immunity required to eliminate measles by maintaining a high coverage of routine first vaccinations in infants, routine second vaccinations at school entry and supplementary local campaigns in high-risk areas. Regular outbreaks of measles are reported, during 2005-2009.Methods: National measles case-based surveillance data collected during 2005-June 2009 was analyzed to assess the epidemiological trend and risk factors associated with measles outbreak in Vietnam.Results: Of the 36,282 measles suspected cases reported nationwide, only 7,086 cases were confirmed through laboratory examination. Although cyclical outbreaks occurred between 2005 and 2009, there was no definite trend in measles outbreaks during these periods. Overall, 2438 of measles confirmed cases were among children ≤5 years and 3068 cases were among people ≥16 years. The distribution with respect to gender skewed towards male (3667 cases) significant difference was not observed (P= 0.1693). Unsurprisingly, 4493 of the confirmed cases had no history of vaccination (X² <0.01). The northern and highland regions were identified as the main endemic foci and the spatial distribution changed with time. The occurrence of cases, in a considerable proportion of vaccinated population, is not only a reflection of the high vaccination coverage in Vietnam but also portrays a possibility of less than 100% vaccine efficacy. More so, in order to prevent measles in adults, high-risk groups must be identified and catch-up for selected groups selected.Conclusions: This study therefore reinforces the need for continued improvement of surveillance system and to probe into the possible role of changes in age-distribution of cases if the effective control of measles is to be achieved.     

Methods for screening the naturally acquired and vaccine-induced immunity to the measles virus

Since the measles, mumps and rubella (MMR) vaccine was introduced into Sweden in 1982, a yearly evaluation of the immunity patterns and sero-conversion rates in 12-year-old children has been carried out. Since 1977, about half of the pre-school children have been vaccinated against measles. This study includes two study groups. (1) 145 selected pre- and post-vaccination samples tested by the haemolysis-in-gel (HIG) technique and the neutralization test (NT). The selection was made from 1298 12-year-old schoolchildren in 1986 and 1987, whose pre-vaccination sera had shown negative or borderline reactions to the HIG technique. (2) Consecutive pre- and post-vaccination samples obtained from 190 vaccinees in 1988 and 1989. These samples were studied by an enzyme-linked, immunosorbent assay (ELISA) and compared to the NT. The NT and the HIG tests yielded congruent results in early post-vaccination sera from children susceptible to measles prior to vaccination. In late post-vaccination samples, the NT and the HIG tests were discordant, up to 25% of the NT-positive samples being negative by the HIG technique. In no instance did the ELISA produce discrepant results, compared with those of the NT. With both this assays significantly lower antibody levels were detected in late post-vaccination sera (8-11 years) compared to early post-vaccination samples (P less than 0.001) or to sera obtained after natural infection.     

Cell mediated immunity after measles in Guinea-Bissau: historical cohort study.

OBJECTIVE: To investigate whether children who have had measles have reduced general cell mediated immunity three years later compared with vaccinated children who have not had measles. DESIGN: Historical cohort study. SETTING: Bissau, Guinea-Bissau. SUBJECTS: 391 children aged 3-13 years who were living in Bissau during a measles epidemic in 1991 and still lived there. These included 131 primary cases and 139 secondary cases from the epidemic and 121 vaccinated controls with no history of measles. MAIN OUTCOME MEASURES: General cell mediated immunity assessed by measurement of delayed type hypersensitivity skin responses to seven recall antigens. Anergy was defined as a lack of response to all antigens. RESULTS: 82 out of 268 cases of measles (31%) were anergic compared with 20 of the 121 vaccinated controls (17%) (odds ratio adjusted for potential confounding variables 2.2 (95% confidence interval 1.2 to 4.0); P 0.009). The prevalence of anergy was higher in secondary cases (33% (46/138)) than in primary cases (28% (36/130)), although this difference was not significant. Anergy was more common in the rainy season (unadjusted prevalence 31% (91/291) than in the dry season (11% (11/98)) (adjusted odds ratio 4.8 (2.2 to 10.3)). This seasonal increase occurred predominantly in the case of measles. CONCLUSION: Reduced general cell mediated immunity may contribute to the higher long term mortality in children who have had measles compared with recipients of standard measles vaccine and to the higher child mortality in the rainy season in west Africa.     

Effect of thermal environment on the temporal,spatial and seasonal occurrence of measles in Ondo state,Nigeria

We investigated the temporal and spatial dynamics, as well as the seasonal occurrence of measles in Ondo state, Nigeria, to better understand the role of the thermal environment in the occurrence of the childhood killer disease measles, which ranks among the top ten leading causes of child deaths worldwide. The linkages between measles and atmospheric environmental factors were examined by correlating human-biometeorological parameters in the study area with reported clinical cases of measles for the period 1998–2008. We also applied stepwise regression analysis in order to determine the human-biometeorological parameters that lead to statistical changes in reported clinical cases of measles. We found that high reported cases of measles are associated with the least populated areas, where rearing and cohabitation of livestock/domestic animals within human communities are common. There was a significant correlation (P < 0.01) between monthly cases of measles and human-biometeorological parameters except wind speed and vapour pressure. High transmission of measles occurred in the months of January to May during the dry season when human thermal comfort indices are very high. This highlights the importance of the thermal environment in disease demographics since it accounted for more than 40% variation in measles transmission within the study period.