The immune status and response to measles vaccine amongst Egyptian infants. A preliminary report.

This study was carried out on 18 infants attending a primary care clinic in the Giza Governorate. Following a comprehensive history and physical exam estimation of measles antibody titer by neutralization testing was carried out on 10 infants prior to vaccination and on 8 infants prior to as well as one month following vaccination against measles utilizing the Edmondston-Zagreb strain. Our results indicate that at the currently adopted age of 9 months for vaccination, infants are susceptible to measles. Good response to vaccination with acquisition of immunity was noted despite border-line levels of growth and development. The occasional patient with persistent maternal antibodies to measles responded well to vaccination.     

Girls may have lower levels of maternal measles antibodies and higher risk of subclinical measles infection before the age of measles vaccination

Background

Previous studies have suggested that girls may have lower maternal measles antibody levels than boys. Girls might therefore be more likely to contract measles infection before the normal age of measles vaccination at 9 months of age.

Methods

In connection with a clinical trial of different measles vaccination strategies, we collected pre-measles vaccination blood samples at 4.5 months of age from two subgroups of children. Samples from these children were used to assess possible differences in maternal antibody levels for boys and girls. At 9 months of age another subgroup of children was sampled before the normal measles vaccination; these samples were used to assess the frequency of subclinical measles infection among boys and girls.

Results

We determined measles-specific antibody levels for 812 children at 4.5 months of age and for 896 children at 9 months of age. At 4.5 months of age girls were less likely to have protective maternal antibody levels, the male–female ratio for protective antibody level being 1.23 (1.00–1.51). Among children sampled at 9 months of age, girls were more likely to have protective levels, the female–male ratio for having protective antibody levels being 1.65 (0.98–2.78) (p = 0.054) and the geometric mean titre was significantly higher for girls (p = 0.007). Children who lived in houses with known measles cases were more likely to have protective levels at 9 months of age even though they had not reported measles infection. Since we had excluded children with known measles infection, girls may have been more likely to have had subclinical measles infection. Combining clinical and possible subclinical measles infection, girls tended to be more likely than boys to contract measles infection before 9 months of age, the RR being 1.36 (0.97–1.90).

Conclusions

Girls lost maternal measles antibodies more rapidly than boys and well before 9 months of age. They may be more likely to contract subclinical measles infection before the current age of measles vaccination.     

小月龄婴儿母传麻疹抗体水平动态变化的纵向研究

目的 研究小月龄婴儿母传麻疹抗体水平的动态变化,探讨减少其感染麻疹病毒的免疫策略。方法 采集2013年7月至2014年4月在广州市某妇幼保健院分娩的母亲及其新生儿出生时(0)、3、5和7月龄血清,采用ELISA检测麻疹IgG抗体,分析母传麻疹抗体水平。结果 共纳入689名母亲及691名新生儿(其中双胞胎2对)。母亲血清麻疹抗体浓度和抗体阳性率分别为513.8 mIU/ml和81.6%,新生儿分别为732.8 mIU/ml和87.3%。新生儿血清麻疹抗体水平与其母亲的血清麻疹抗体水平呈正相关(r=0.9175,P<0.001)。婴儿自出生后体内的麻疹抗体水平在3月龄时迅速下降,至7月龄时基本转为阴性。低、中抗体水平组婴儿在3月龄时抗体水平均已转为阴性,而高抗体水平组的婴儿在5月龄时抗体水平仍为阳性。结论 不同免疫状态母亲的婴儿其母传麻疹抗体水平在8月龄前已基本无法保护婴儿免于感染麻疹,建议适当调整婴儿麻疹疫苗初免月龄,并提高育龄期妇女麻疹抗体水平,以减少小月龄婴儿麻疹发病。     

陕西省麻疹高接种率和高发病率的原因分析

目的探讨陕西省麻疹高接种率下高发病率的病原学和疫苗免疫相关因素。方法分析麻疹病例年龄及免疫史。从咽拭子中分离病毒，用酚-氯仿抽提法提取病毒RNA，逆转录一聚合酶链反应（RT—PCR）扩增N基因-COOH端的450个核苷酸（bp）片段，进行序列测定和基因分型。用微量中和试验测定疫苗免疫血清及麻疹病例急性期血清中和疫苗株和野毒株的抗体水平。结果麻疹病例中有麻疹疫苗免疫史的平均占38．97％；麻疹病例急性期血清：有免疫史的中和S191株GMT（56．18）明显高于H1野毒株GMT（26．90）；无免疫史的S191株GMT（25．40）与H1野毒株（27．86）相近。疫苗免疫血清：S191株抗体效价≤16血清中有19．15％为H1野毒株抗体阴性。结论陕西省近年出现的麻疹高接种率水平下的高发病率现象不排除麻疹流行株变异和疫苗对流行株H1基因组野毒株保护性不足两方面因素。     

Cost-effectiveness of three different vaccination strategies against measles in Zambian children

The vaccination program in Zambia includes one dose of measles vaccine at 9 months of age. The objective of this study was to compare the cost-effectiveness of the current one-dose measles vaccination program with an immunization schedule in which a second dose is provided either through routine health services or through supplemental immunization activities (SIAs). We simulated the expected cost and impact of the vaccination strategies for an annual cohort of 400,000 children, assuming 80% vaccination coverage in both routine and SIAs and an analytic horizon of 15 years. A vaccination program which includes SIAs reaching children not previously vaccinated would prevent on additional 29,242 measles cases and 1462 deaths for each vaccinated birth cohort when compared with a one-dose program. Given the parameters established for this analysis, such a program would be cost-saving and the most cost-effective vaccination strategy for Zambia.     

2012年元谋县麻疹传播因素调查分析

目的分析2012年元谋县麻疹病例发生的原因,以便采取更为有效、科学的麻疹防控措施,为最终实现消除麻疹的目标提供科学参考依据。方法用统一设计的表格对病例进行个案调查,对病例村开展麻疹传播危险因素调查;用随机抽样方法抽取30个村委会开展麻疹接种率调查;制定麻疹IgG抗体滴度检测方案,随机抽取两个村委会不同年龄段的人群和到县人民医院就诊的不同年龄段的人群共406人开展麻疹抗体滴度检测。结果2012年元谋县发生4例麻疹散发病例,4例病例中无免疫史2例,基础免疫史不详1例,有免疫史1例;发病年龄8月龄～17月龄3例,8岁1例;对4例病例村开展麻疹传播危险因素调查结果表明,疫点周围无麻疹传播危险因素;对30个村委会的8月龄至4岁共240名儿童开展麻疹接种率调查,含麻疹成份疫苗的接种率达100％,对不同年龄段的人群共406人开展麻疹抗体滴度检测,麻疹抗体滴度〈200MIU／mL2人,≥200MIU／mL137人,≥800MIU／mL267人,抗体阳性率达99．51％,抗体保护率达65．76％,抗体保护率最高为18月～5岁组,达89．09％,最低20～34岁组,为40．00％,各年龄组间抗体保护率有显著性差异（χ^2=50．81,P〈0．005）。结论元谋县适龄儿童麻疹疫苗接种率较高,基础免疫工作扎实,麻疹抗体阳性率较高。2012年发生的麻疹病例均为散发,发生麻疹流行和暴发的可能性不大。麻疹发病的主要原因是个别儿童存在免疫空白,今后要加强对个别免疫空白人群的麻疹疫苗接种工作,提高及时接种率,消除免疫空白人群。     

云南省华宁县健康人群麻疹抗体水平分析

目的掌握云南省华宁县健康人群麻疹疫苗接种率和麻疹IgG的抗体水平,探索免疫薄弱环节,为提高该县免疫规划工作提供科学依据。方法采取分层整群抽样方法,在华宁县辖区内随机抽取9个接种点,分8个年龄组（8—17和18—23月龄,2—3、4—5、6—9、10～13、14—17和≥18岁）进行麻疹疫苗接种率调查和麻疹IgG抗体水平检测,每个年龄组40—50人,共检测394人。采用酶联免疫吸附试验检测血清中的麻疹IgG抗体水平。结果调查的394人中麻疹疫苗接种率为85．53％,有效保护率为85．02％,抗体阳性率为98．48％,GMT为1：643;不同接种点麻疹疫苗接种有效保护率、GMT差异有统计学意义（P〈0．01）;各年龄组间麻疹疫苗接种率、抗体阳性率、有效保护率、GMT差异均有统计学意义（P〈0．01）,低龄组相对较低。结论华宁县健康人群麻疹疫苗接种已取得理想的免疫效果,但须进一步提高低龄组婴儿及时接种率,关注流动儿童和大龄儿童,特别是非免疫规划人群的保护。     

Serological and epidemiological effects and influence factors of primary immunization with current live attenuated measles vaccine (Hu191) among infants aged 6-15 months

A study of the serological and epidemiological effects of primary immunization with current live attenuated measles vaccine (Hu191) among 503 children aged 6-15 months, was conducted in Jingzhou, Hubei province, China from 1991 to 1998. The results showed that the positive conversion rate of measles IgG was 91.65%, geometric mean titer (GMT) was 1:266.74 and its ratio reaching protective titer was 46.52% at 1 month after first immunization. As time goes on, the above-mentioned indexes reduced rapidly. Short-term and long-term efficacy of 0.2, 0.3 and 0.5 ml measles vaccine was similar. The positive conversion rate, GMT and ratio of protective titer of IgG of different potency measles vaccine were not significantly different, however, latter two indexes showed a tendency to increase gradually with the rise of vaccine potency. The age for primary immunization was a main factor influencing immune response to measles vaccine. Immune efficacy of 6 months old group by primary vaccination was significantly lower than those of > or = 8 months old group. The result indicated it is practicable that infant aged 8 months be vaccinated with measles vaccine in China. Twenty-nine suspected measles cases were reported, out of them, 26 cases were negated in time from December 1991 to November 1998. The study showed that the short-term positive conversion rate of the enzyme immune assay IgG antibody of the Hu191 is higher, but its serological endurance isn't ideal, and its epidemiological effect should be evaluated further.     

Evaluation of an early two-dose measles vaccination schedule.

Vaccination at 6 months of age followed by routine revaccination is recommended when exposure of infants to measles is likely. Dade County, Florida, began this early two-dose schedule during a large epidemic in 1986-1987 (i.e., 22% of cases occurred in infants aged 6-11 months). This schedule was continued routinely in high-risk areas. The effect of an early two-dose schedule on measles prevention in the county was examined by comparing measles vaccination coverage and epidemiology before (1985-1987) and after (1988-1996) the schedule became routine. To assess serologic response, seroprevalence of measles antibody among children aged 4-6 years in 1995 was examined. To evaluate vaccine effectiveness, a case-control study was conducted among preschool-aged children. Among those aged 2 years, vaccination coverage with > or =1 dose increased from 75% to 94% in 1996. The number of annual cases declined, and endemic measles transmission reportedly ended after 1993. Seroprevalence of plaque reduction neutralization antibody (titer > 1:120) among those receiving vaccination according to an early two-dose schedule and a single dose at age > or =12 months was 94% (95% confidence interval: 89, 98) and 98% (95% confidence interval: 95, 100). In these groups, vaccine effectiveness was comparably high. Early two-dose measles vaccination is associated with improved coverage and a comparably high level of humoral immunity and clinical protection as a single dose at age > or =12 months. This strategy can be useful in areas at high risk for measles among infants.     

Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy.

BACKGROUND: Previous studies from Africa have suggested that there is little benefit to be gained from early two-dose measles vaccination schedules. Two-dose schedules have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting of the antibody response. Because of the poor results achieved previously with two-dose measles vaccination schedules, we studied patterns of participation, reasons for non-participation, vaccination coverage and relative efficacy of a one-dose versus a two-dose schedule in connection with the implementation of an early two-dose trial in Guinea-Bissau. METHODS: Children born from September 1994 to January 1996 were randomized into two groups receiving either two doses of measles vaccine at 6 and 9 months or one dose of inactivated polio vaccine (IPV) at 6 months and measles vaccine at 9 months. RESULTS: At 6 months of age 86% (1869/2181) of the children participated, and at 9 months of age participation was 87% (1775/2035). The return rate for obtaining a second dose of vaccine was 93% (1647/1773). The main reason for not participating was travelling (78%). Around 50% of those who did not take part in one vaccination took part in the other. When only children participating the first time they were called for a measles vaccination were included, the measles vaccination coverage in the one-dose group was 59% versus 80% in the two-dose group, i.e. a 50% reduction in the risk of not being vaccinated (relative risk [RR] 0.50; confidence interval [CI]: 0.43-0.57). Few measles cases have occurred in the study area since the implementation of the trial making precise estimation of the relative efficacy of the two vaccine strategies difficult, but all seven clinically diagnosed measles cases occurred in the one-dose group making the relative efficacy for the two-dose group compared with the one-dose group 100% (95% CI: 35%-100%; two-tailed P = 0.016). When including maternal reports, the relative efficacy was 90% (95% exact confidence interval; two-tailed P = 25%-97%, P = 0.022). CONCLUSION: In this study of a two-dose measles immunization schedule at 6 and 9 months of age there was no sign of low participation or poor return rates. The risk of not being vaccinated was lower in the two-dose group than in the one-dose group, and the relative efficacy of a two-dose versus a one-dose schedule was high. Although our results were obtained within a trial where dedicated personnel informed every participant personally about the study, we believe our results indicate that with thorough information about the population it may be possible to achieve a higher coverage with a two-dose measles vaccination schedule than a one-dose schedule. A two-dose schedule may be a feasible way to resolve the problems of low coverage and severe measles infection among infants.     

北京市通州区6月龄儿童麻疹疫苗免疫效果分析

目的探讨麻疹疫苗的初免月龄提前至6月龄的可行性。方法通过与8月龄婴儿的比较,分析6月龄婴儿的免后麻疹IgG抗体滴度、阳转率。结果免疫前IgG滴度,6月龄免前麻疹IgG滴度高于8月龄,只有6.06%的6月龄婴儿处于低保护水平;免疫后6月龄、8月龄婴儿麻疹IgG滴度平均分别为751.44mIU/ml、1076.14mIU/ml,8月龄的免后麻疹IgG滴度高于6月龄(P=0.003);6月龄、8月龄免后麻疹IgG阳转率分别为93.55%、96.88%,差异无统计学意义(P=0.978)。结论6月龄以后的婴幼儿处于麻疹易感状态,在现有2剂(8月龄、1.5岁)麻疹疫苗免疫的基础上,将初免月龄提前至6月龄,既能保证麻疹疫苗的高覆盖率,又能减少小年龄组的麻疹发病率。     

Study of incidence of measles and vaccination coverage in Ahmedabad urban slums

Measles incidence and vaccination coverage survey was carried out in Ahmedabad urban slums in February 2000. A total of 3073 children between 9 to 59 months were studied. The incidence rate of measles was 11.2% (95% C.I-10.04-12.36). Measles vaccination coverage was only 59.88%. There was no gender difference in vaccine coverage or measles incidence rate. Diarrhoea was the most common complication observed among both vaccinated and unvaccinated children and it was significantly more among unvaccinated children. Among 1840 vaccinated children only 529 (28.75%) children received vitamin A along with measles vaccination.     

Immune response to measles vaccine in Peruvian children.

OBJECTIVE: To evaluate the immune response in Peruvian children following measles vaccination. METHODS: Fifty-five Peruvian children received Schwarz measles vaccine (about 10(3) plaque forming units) at about 9 months of age. Blood samples were taken before vaccination, then twice after vaccination: one sample at between 1 and 4 weeks after vaccination and the final sample 3 months post vaccination for evaluation of immune cell phenotype and lymphoproliferative responses to measles and non-measles antigens. Measles-specific antibodies were measured by plaque reduction neutralization. FINDINGS: The humoral response developed rapidly after vaccination; only 4 of the 55 children (7%) had plaque reduction neutralization titres <200 mlU/ml 3 months after vaccination. However, only 8 out of 35 children tested (23%) had lymphoproliferative responses to measles antigens 3-4 weeks after vaccination. Children with poor lymphoproliferative responses to measles antigens had readily detectable lymphoproliferative responses to other antigens. Flow cytometric analysis of peripheral blood mononuclear cells revealed diffuse immune system activation at the time of vaccination in most children. The capacity to mount a lymphoproliferative response to measles antigens was associated with expression of CD45RO on CD4+ T-cells. CONCLUSION: The 55 Peruvian children had excellent antibody responses after measles vaccination, but only 23% (8 out of 35) generated detectable lymphoproliferative responses to measles antigens (compared with 55-67% in children in the industrialized world). This difference may contribute to the less than uniform success of measles vaccination programmes in the developing world.     

Options for improvement of the Dutch measles vaccination schedule

We investigated which vaccination schedule gives best protection to the vaccinating population, in case of a measles epidemic in pockets of unvaccinated individuals. We explored the effect of an additional measles vaccination (at 6 or 9 months), advancing the first measles-mumps-rubella (MMR) vaccination from 14 to 11 months, and advancing the second MMR from 9 to 4 years. Measures of protection among vaccinees (percentage of susceptibles, number of reported cases, percentage of lifetime spent susceptible) were estimated with a mathematical model of the impact of antibody level on seroconversion and immunity. Advancing the age of second MMR vaccination prevents considerably more cases among vaccinees than an extra early measles vaccination or advancing the age of first MMR vaccination.     

Continuing measles transmission in students despite school-based outbreak control program

FRom September 9, 1981 to January 5, 1982, a measles outbreak occurred in Warren County, Pennsylvania. The outbreak persisted for nine weeks following the implementation of a county-wide outbreak control program primarily consisting of identifying and vaccinating susceptible schoolchildren. Forty-six cases occurred among students more than two weeks after control program implementation. All 46 had a school record indicating adequate measles vaccination; 13 had been vaccinated at control program clinics by one jet-injector team (Team A). A seroprevalence survey demonstrated that persons vaccinated by Team a had a significantly higher rate of vaccination failure than children vaccinated by other teams (37.0% vs. 5.9%, p = 5.7 X 10(-7). A case-control study was undertaken to assess possible additional risk factors for developing measles. Individuals with measles were nine times more likely than control individuals to have records of measles immunization that could not be verified with providers or to have been vaccinated at 12 months of age. The most likely reasons that this outbreak was sustained among persons with adequate vaccination histories were: 1) impotent vaccines and/or improper vaccine administration techniques were used by one jet-injector team; 2) several persons with histories of adequate vaccination were really not adequately vaccinated; adn 3) a substantial number of persons had been vaccinated at 12 months of age. There is no evidence from this outbreak that transmission of measles can be sustained among the 2-10% of individuals expected to remain susceptible following a single appropriate measles vaccination.     

Recent immunization against measles does not interfere with the sero-response to yellow fever vaccine

In order to determine whether previous measles vaccination interferes with the sero-response to yellow fever vaccine, 294 children at nine months of age were randomly assigned to immunization with yellow fever vaccine at different time intervals after measles vaccination. The seroconversion rate (SCR) and the log10 geometric mean titer (GMT) for 17 DD yellow fever vaccine at different intervals after Schwarz measles vaccination were: 1-6 days: SCR = 44/57 = 77%; GMT = 4.57; 7-13 days: SCR = 36/53 = 68%; GMT = 4.46; 14-21 days: SCR = 55/65 = 85%; GMT = 4.46; 22-27 days: SCR = 41/54 = 76%; GMT = 4.41 and >28 days: SCR = 52/65 = 80%; GMT = 4.24 (p > 0.05). We conclude that recent immunization against measles does not interfere with the sero-response to yellow fever vaccine.     

Comparative results of the immunogenicity of Edmonston-Zagreb and Schwartz measles vaccines administered to 60 Egyptian infants.

The present study was conducted on sixty 9-11 month infants attending a primary care clinic in a rural Giza governorate area. Patients were divided into two groups: the first group comprised 42 infants who were vaccinated with the Edmonston Zagreb measles vaccine strain, whereas the second group comprised 18 infants who were vaccinated with the Schwartz measles vaccine strain. Estimation of measles antibody titer by neutralization testing was determined by the microtiter technique prior to and 4 weeks post vaccination. The overall serconversion rate was 85%. Three infants failed vaccination. The Edmonston-Zagreb strain was superior to the Schwartz strain in inducing immunity to non immune infants. The nutritional status of the study group was abnormal in almost 1/2 (29/60) infants and borderline in 1/3 (20/60).     

Immunogenicity and efficacy of one dose measles-mumps-rubella (MMR) vaccine at twelve months of age as compared to monovalent measles vaccination at nine months followed by MMR revaccination at fifteen months of age

BACKGROUND AND METHODS: measles is a common cause of morbidity and mortality in developing countries. Although the measles-mumps-rubella vaccine (MMR) is currently in use in developed countries, monovalent measles vaccine (MV) is routinely recommended by World Health Organization (WHO) at 9 months of age in Turkey, as in many other developing countries. In this study, 442 Turkish children received MV at 9 months of age and were revaccinated with MMR vaccine at 15 months of age. In the second group 495 children received MMR at 12 months of age with no earlier measles vaccination. Antibodies were measured before the first vaccination and 6 weeks after the MMR. All children had been followed for occurrence of measles infection for 60 months. Two vaccination schedules were compared for immunogenicity and protection rates. CONCLUSIONS: seroconversion and clinical protection rates were significantly higher in children who received only MMR at 12 months of age than in children revaccinated at 15 months of age. Seroconversion rate for measles was 69.9% in children who received MMR at 12 months of age and 90.3% in children revaccinated at 15 months of age (P=0.0003). While there was no measles case in children who were revaccinated, 12 (2.7%) children in the first group acquired measles during the follow-up period. Vaccination at 12 months of age appeared to be better than the current national standard. The late elimination of maternal antibodies and the inhibitory effect of a weak antibody response after the first dose of vaccine at 9 months may explain the better immunogenicity and efficacy of the MMR vaccine given at 12 months of age.     

Mass measles vaccination in urban Burkina Faso, 1998

OBJECTIVE: To assess the impact of the National Immunization Days (NIDs) on measles vaccine coverage in Burkina Faso in 1998. METHODS: During the week after the campaign, in which measles vaccine was offered to children aged 9-59 months in six cities regardless of vaccination history, a cluster survey was conducted in Ouagadougou and Bobo Dioulasso, the country's two largest cities. Interviewers visited the parents of 1267 children aged up to 59 months and examined vaccination cards. We analysed the data using cluster sample methodology for the 1041 children who were aged 9-59 months. FINDINGS: A total of 604 (57%) children had received routine measles vaccination prior to the campaign, and 823 (79%) were vaccinated during the NIDs. Among those who had previously had a routine vaccination, 484 (81%) were revaccinated during the NIDs. Among those not previously vaccinated, 339 (78%) received one dose during the NIDs. After the campaign, 943 (91%) children had received at least one dose of measles vaccine. Better socioeconomic status was associated with a higher chance of having been vaccinated routinely, but it was not associated with NID coverage. CONCLUSION: The mass campaign enabled a substantial increase in measles vaccine coverage to be made because it reached a high proportion of children who were difficult to reach through routine methods.