Current epidemiology of rubella and congenital rubella syndrome in Australia: progress towards elimination

This study evaluates the evidence for elimination of rubella and congenital rubella syndrome (CRS) in Australia, drawing on three national serosurveys conducted between 1996 and 2007 and supported by statutory notification and vaccine coverage data. Anti-rubella IgG seropositivity was defined as ≥ 10 IU/ml by EIA. Between 1998 and 2007, rubella notifications fell >100-fold, to an average of 2 cases per million and there were five confirmed cases of CRS, two of which were locally acquired in 2003. Weighted overall seropositivity remained constant among 1-49 year-olds (89.6% in 1999; 88.1% in 2007). Between 2002 and 2009, 95% of children received at least one dose of the measles-mumps-rubella (MMR) vaccine. All three serosurveys provided estimates for R less than 0.5, well below the epidemic threshold of 1. All available data are supportive of Australia being considered for elimination status. Further reductions in incidence of CRS will require continued attention to vaccine coverage in overseas-born women, as well as the maintenance of current high coverage level of two-dose MMR vaccination.     

Modelling rubella in Europe

The prevention of congenital rubella syndrome (CRS), as a complication of rubella infection during pregnancy, is the main aim of rubella vaccination programmes. However, as vaccination of infants leads to an increase in the average age at which those who were not immunized become infected, certain rubella vaccination programmes can lead to an increase in the incidence of CRS. In this paper we use a mathematical model of the transmission dynamics of rubella virus to investigate the likely impact of different vaccination policies in Europe. The model was able to capture pre- and post-vaccination patterns of infection and prevalence of serological markers under a wide variety of scenarios, suggesting that the model structure and parameter estimates were appropriate. Analytical and numerical results suggest that endemic circulation of rubella is unlikely in Finland, the United Kingdom, The Netherlands, and perhaps Denmark, provided vaccine coverage is uniform across geographical and social groups. In Italy and Germany vaccine coverage in infancy has not been sufficient to interrupt rubella transmission, and continued epidemics of CRS seem probable. It seems unlikely that the immunization programmes in these countries are doing more harm than good, but this may be partly as a result of selective immunization of schoolgirls. Indeed, in both these countries, selective vaccination of schoolgirls with inadequate vaccination histories is likely to be an important mechanism by which CRS incidence is suppressed (unlike the other countries, which have had sufficiently high infant coverage rates to withdraw this option). Reducing inequalities in the uptake of rubella vaccine may bring greater health benefits than increasing the mean level of coverage.     

Seroprevalence of rubella in the cord blood of pregnant women and congenital rubella incidence in Nha Trang,Vietnam

To investigate susceptibility to and factors associated with rubella infection among pregnant mothers and to estimate the burden of congenital rubella infection (CRI) in Vietnam where rubella-containing vaccine (RCV) is not included in the routine immunization program, we conducted a prospective cohort study in Nha Trang, Vietnam between 2009 and 2010. Rubella-specific immunoglobulin-M and immunoglobulin-G were investigated in cord blood samples by enzyme immunoassay. Corresponding clinical–epidemiological data were analyzed and the national congenital rubella syndrome (CRS) incidence was estimated using modeling. We enrolled 1988 pairs of mothers aged 17–45 years and their newborn babies. No mothers had received RCV. Multivariate analysis revealed that mothers aged 17–24 (aOR 2.5, 95% CI: 1.7–3.8) or 25–34 (1.4, 1.0–2.1) years were more likely to be susceptible than those aged 35–45 years. Overall 28.9% (574/1988, 95% CI: 26.9–30.9%) of mothers were seronegative. The CRI rate was 151 (95% CI: 0–322) per 100,000 live births. Modeling estimated that 3788 babies (95% CI: 3283–4143) were born with CRS annually in Vietnam with an overall CRS incidence of 234 (95% CI: 207–262) cases per 100,000 live births. A substantial proportion of women of childbearing age (WCBA) are at risk of rubella infection during pregnancy and this can result in a high frequency of miscarriage or burden of CRS across Vietnam. Prompt introduction of RCV into national immunization program with catch-up vaccination to children and WCBA will reduce CRI in Vietnam.     

Sero-epidemiology of rubella in the urban population of Addis Ababa, Ethiopia

We conducted a community-based cluster sample survey of rubella sero-epidemiology in Addis Ababa, Ethiopia in 1994. Among 4666 individuals for whom complete data were available, rubella antibody prevalence was 91% (95% confidence interval: 90, 92). On multivariable analysis, seroprevalence was lower among individuals who were resident in Addis Ababa for 1 year or less. Approx. 50% seroprevalence was attained by age 4 years, and the estimated average age at infection was 5.2 years. The highest age-specific force of infection was estimated to occur in 5- to 9-year-olds. The early age at infection corresponded with a low estimated incidence of congenital rubella syndrome (CRS) of 0.3 per 1000 live births, equivalent to nine cases of CRS in 1994. The predicted critical level of immunity for elimination of rubella via vaccination was 85-91%, requiring 89-96% coverage with a vaccine of 95% effectiveness. Unless very high coverage of rubella vaccine could be guaranteed, the introduction of childhood vaccination could increase the incidence of CRS in Addis Ababa.     

Control of rubella and congenital rubella syndrome (CRS) in developing countries, Part 2: Vaccination against rubella.

In 1995-96 we conducted a review of rubella immunization strategies. Worldwide, 78 countries (more than one-third) reported a national policy of using rubella vaccine. This was closely related to country economic status. Based on the United Nations country classification, rubella vaccine is used in 92% of industrialized countries, 36% of those with economies-in-transition, and 28% of developing countries. Cases of congenital rubella syndrome (CRS) may be prevented as follows: by providing direct protection to women and/or schoolgirls (a selective vaccination strategy); by vaccinating boys and girls to provide indirect protection by reducing the transmission of rubella virus (a childhood vaccination strategy); or by a combination of these approaches (a combined strategy). A combined strategy was most commonly reported (60% of countries); seven countries (9%) reported a selective strategy; and 24 countries (31%) reported only childhood immunization. Experience has shown that it is essential to include vaccination of women of childbearing age in any rubella control strategy. Childhood vaccination alone may pose a risk of an increase in CRS cases. Although many countries have introduced rubella vaccine, few report any data on the impact of vaccination. Countries using rubella vaccine need to establish surveillance for rubella and CRS and monitor coverage in each of the target groups.     

Informing rubella vaccination strategies in East Java,Indonesia through transmission modelling

An estimated 110,000 babies are born with congenital rubella syndrome (CRS) worldwide annually; a significant proportion of cases occur in Southeast Asia. Rubella vaccine programs have led to successful control of rubella and CRS, and even the elimination of disease in many countries. However, if vaccination is poorly implemented it might increase the number of women reaching childbearing age who remain susceptible to rubella and thereby paradoxically increase CRS. We used an age-structured transmission model to compare seven alternative vaccine strategies for their impact on reducing CRS disease burden in East Java, a setting which is yet to implement a rubella vaccine program. We also investigated the robustness of model predictions to variation in vaccine coverage and other key epidemiological factors. Without rubella vaccination, approximately 700 babies are estimated to be born with CRS in East Java every year at an incidence of 0.77 per 1000 live births. This incidence could be reduced to 0.0045 per 1000 live births associated with 99.9% annual reduction in rubella infections after 20 years if the existing two doses of measles vaccine are substituted with two doses of measles plus rubella combination vaccine with the same coverage (87.8% of 9-month-old infants and 80% of 6-year-old children). By comparison a single dose of rubella vaccine will take longer to reduce the burden of rubella and CRS and will be less robust to lower vaccine coverage. While the findings of this study should be informative for settings similar to East Java, the conclusions are dependent on vaccine coverage which would need consideration before applying to all of Indonesia and elsewhere in Asia.     

Humoral immunogenicity to measles,rubella, and varicella-zoster vaccines in biliary atresia children

To investigate the humoral immune response to measles, rubella, and varicella-zoster virus (VZV) vaccines in biliary atresia (BA) children before liver transplantation, we conducted the cross-sectional designed study. Fifty BA children (age, 3.6 ± 0.2 years; 24 girls) who had not yet received liver transplantation, and another 150 healthy controls (age, 4.0 ± 0.1 years; 78 girls) were recruited into this study to evaluate their primary humoral immune response to measles, rubella, and VZV vaccines. All of these BA children (n = 50) and controls (n = 150) received one dose of measles, one dose of measles–mumps–rubella (MMR), and one dose of VZV vaccine before our assessment. Serum samples were collected at least 1 month after the vaccination and serum immunoglobulin G (IgG) antibody to measles, rubella, and VZV were then determined by qualitative enzyme-linked immune-sorbent assay. The prevalence of seropositive rate of measles IgG antibody (84% vs. 96.7%; P = 0.002), rubella (82.0% vs. 98.7%; P < 0.001), and VZV (74% vs. 95.3%; P < 0.001) were significantly different between BA children and the controls after regular measles, MMR, and VZV vaccination before 2 years of age. In those BA children with seronegative VZV antibody after vaccination, two had VZV infection after the liver transplantation. This study indicated that humoral immunity to rubella, measles and VZV vaccines are significantly lower in BA children than the normal population by standard vaccine schedule.     

Seroprevalence of measles and rubella antibodies in pregnant women Haiti, 2012

Background

Haiti had set a national goal to eliminate measles and rubella, as well as congenital rubella syndrome (CRS) by 2010. A 2007–2008 nationwide measles and rubella vaccination campaign targeting 1–19 years, however, reached only 79% of the target population. To assess whether population immunity was adequate to support elimination, we conducted a national serosurvey.

Methods

We systematically selected 740 serum specimens collected from pregnant women in a 2012 national antenatal HIV sentinel serosurvey across four age strata: 15–19, 20–24, 25–29 and 30–39 years. Sera were tested for measles and rubella specific immunoglobulin G antibodies (IgG) using commercial immunoassays. We classified sera as seropositive, seronegative or indeterminate per manufacturer's instructions, and analyzed seroprevalence according to age strata, and rural or urban residence. We assessed immunity by estimating antibody concentrations in international units per milliliter (IU/mL) for seropositive and indeterminate sera. Measles IgG concentrations >0.12 IU/mL and rubella IgG concentrations >10 IU/mL were considered clinically protective.

Results

Of 740 sera, 696 (94.1%) were seropositive and 20 (2.7%) were indeterminate for measles IgG; overall 716 (96.8%) sera had IgG concentrations >0.12 IU/mL. For rubella IgG, 691 (93.4%) sera were seropositive and 1 (0.1%) was indeterminate; a total of 687 (92.8%) had IgG concentrations >10 IU/mL. Measles seropositivity varied across age strata (p = 0.003); seropositivity increased from 88.6% among 15–19 year olds to 98.4% among 30–39 year olds (Cochran–Armitage trend test ≤ 0.0001). Rubella seropositivity did not differ across age strata. There were no statistically significant differences in measles or rubella seropositivity by urban versus rural residence.

Conclusion

Despite previous low vaccination coverage for measles, results from this serosurvey indicate high levels of measles and rubella seropositivity in pregnant women, and contribute to the evidence for measles, rubella and CRS elimination from Haiti by the target date.     

An epidemiological assessment towards elimination of rubella and congenital rubella syndrome in Singapore

ObjectiveIn line with regional and global goals for the elimination of rubella and congenital rubella syndrome (CRS), we reviewed the epidemiological situation in Singapore, based on surveillance reports on rubella and CRS, national immunization coverage and seroprevalence surveys. The aim of our review was to identify current gaps and steps taken to achieve the targets set by the World Health Organization (WHO) Western Pacific Regional Office (WPRO).MethodsEpidemiological data on clinical and laboratory-confirmed rubella cases, including CRS, notified to the Communicable Diseases Division, Ministry of Health, Singapore, from 2003 to 2013 were collated and analyzed. Vaccination coverage against rubella was obtained from the National Immunization Registry and School Health Services of the Health Promotion Board. The changing prevalence of rubella was determined from periodic serological surveys.FindingsThe incidence of indigenous rubella cases per million population decreased from 37.2 in 2008 to 7.6 in 2013 and there had been no indigenous case of CRS in 2012 and 2013. Therapeutic abortions performed due to rubella infections had become uncommon. The annual measles, mumps, and rubella (MMR) vaccination coverage in childhood population remained high ranging from 93% to 96%. The overall susceptibility to rubella in women aged 18–44 years had reduced significantly from 15.8% in 2004 to 11.0% in 2010. The prevalence of IgG antibody against rubella among Singapore children aged 1–17 years was maintained at 87.3% in 2008–2010.ConclusionAll available data indicated that Singapore has made good progress towards the elimination of rubella and CRS. It has attained the targets set by the WHO WPRO for 2015. In preparation for verification of rubella elimination, an enhanced surveillance system has been implemented to ensure that all reported cases are laboratory confirmed, and genotyping of rubella virus strains isolated is carried out to provide evidence for interruption of endemic transmission.     

The epidemiology of rubella and congenital rubella in Australia, 1992 to 1997.

Selective rubella vaccination of schoolgirls commenced in 1971 and was followed by a significant reduction in congenital rubella. Infant vaccination with MMR was introduced in 1989 to interrupt circulation of the virus in young children, and in 1994/95 the adolescent school based rubella vaccination program was changed to MMR for both boys and girls. This report reviews the epidemiology of rubella and congenital rubella between 1992 and 1997 using reports to the National Notifiable Diseases Surveillance System (NNDSS) and the Australian Paediatric Surveillance Unit (APSU). Notification rates for rubella exceeded 20 per 100,000 in 1992, 1993 and 1995 and declined to 7.2 per 100,000 in 1997. Sixty-one per cent of notifications occurred between September and December and 68% occurred in males. The incidence rate in males aged 15-22 years peaked at 152.6 per 100,000 in 1995 reflecting the lack of immunisation in this cohort. From 1993 to 1997, 19 children were reported with congenital rubella syndrome, representing 1 in 67,000 live births. Of these, 17 had multiple defects (4 died) and 2 had deafness only. There were also 5 infants with congenital rubella infection but no defects. Australia's rate of congenital rubella syndrome exceeded that of the United Kingdom and the United States of America but this may be partly attributable to differences in reporting practices. The impact of changing the second dose of MMR vaccine to 4 years of age in 1998 will require careful monitoring.     

Safety and immunogenicity of a measles–mumps–rubella–varicella vaccine given as a second dose in children up to six years of age

Two doses of measles–mumps–rubella vaccine (MMR) are widely recommended and consideration is being given to a similar schedule for varicella vaccine. A combined measles–mumps–rubella–varicella vaccine (MMRV) could be considered for this second dose in children previously vaccinated separately with MMR and varicella vaccines. Healthy children (N = 390) aged 15–75 months (median 54 months) previously immunized with MMR and varicella vaccines were randomly allocated to receive MMRV or separate injections of MMR and varicella vaccines. Before administration of study vaccines, seropositivity rates were 96.4% for measles, 94.3% for mumps, 99.5% for rubella, and 97.9% for varicella. Post-immunization, seropositivity rates were 99.5% for measles and mumps and 100% for rubella and varicella in the MMR + varicella group and 100% for all four antigens in the MMRV group; a 26.2- and 27.2-fold increase in varicella titer was observed in the MMR + varicella vaccine and MMRV groups, respectively. Except for more frequent pain in the MMRV group (33.3% vs. 23.7%, p = 0.043), there were no differences in the incidence of local and solicited symptoms between groups. In children primed with MMR and varicella vaccine, MMRV had non-inferior immunogenicity and similar safety profiles as a second dose of licensed MMR and varicella vaccine administered concomitantly.     

The predicted impact of private sector MMR vaccination on the burden of Congenital Rubella Syndrome

In many developing countries, Measles-Mumps-Rubella (MMR) vaccine is available through the private but not the public sectors, and there is no systematic rubella vaccination among adult women. In this paper, we extend previous modeling studies to demonstrate that in developing countries with a medium-high force of infection (200-400/1000 per year), current levels of private sector MMR coverage (<60%) would lead to increases in the incidence of Congenital Rubella Syndrome (CRS) both among unvaccinated individuals and the general population even when mixing between vaccinated and unvaccinated individuals is fairly minimal. Our findings highlight the need for countries to establish surveillance of trends in susceptibility to rubella and CRS incidence and perhaps introduce rubella vaccination among women of child-bearing age.     

A systematic review of rubella vaccination strategies implemented in the Americas: impact on the incidence and seroprevalence rates of rubella and congenital rubella syndrome

Objective

To evaluate the impact of rubella vaccination strategies on the rates of acquired rubella and congenital rubella syndrome in the Americas.

Methods

We conducted a systematic review of the literature (MEDLINE, PubMed, EMBASE, Cochrane Library, Artemisa Database, LILACS Database, Evidence Portal, VHL-PAHO Portal, Scielo, and Grey-Literature sources) that was published from 1969–2010. We included studies on rubella incidence and seroprevalence rates that were associated with rubella vaccination. The quality of the studies was evaluated according to international guidelines.

Results

A total of 14 studies were identified: 2 clinical trials, 2 cohort studies, 3 transversal studies, 5 ecological studies, and 2 mathematical models. Childhood vaccination reduced the incidence of rubella by 23.6% to 99.6%, increased the occurrence of epidemic cycles in Argentina and in the United States, and shifted the illness to susceptible adults. Vaccination strategies that focused on women and children in Brazil were associated with a 5.5-fold greater incidence of rubella in men leading to new outbreaks and CRS. A combined vaccination strategy with a universal approach that included routine vaccination for boys, girls, women, and men in Mexico and in Costa Rica reduced the incidence of rubella by more than 98% and led to absence of CRS since 2008. A medium and a low risk of bias were found in 3 and 4 articles, respectively.

Conclusion

The results of this review demonstrate that the combined vaccination strategy with a universal approach was the most effective strategy as evidenced by a drastic reduction in the number of cases and the interruption of endemic transmission of rubella in the Americas.     

Modelling the incidence of congenital rubella syndrome in developing countries

BACKGROUND: As of 1997, less than one-third of developing countries included rubella vaccine in their national immunization programme. In countries that have achieved high coverage of measles vaccine, an ideal opportunity exists to include control of rubella and congenital rubella syndrome (CRS) in enhanced measles control activities. Data on the burden of congenital rubella syndrome are important to guide rubella vaccination policies. METHODS: We reviewed the literature to identify studies of rubella antibody prevalence in developing countries that were conducted on populations with no major selection bias, prior to wide-scale rubella vaccination in the country. We used a simple catalytic model to describe the age-specific prevalence of susceptibility to rubella virus infection in given populations. Estimates of the incidence of infection among pregnant women were calculated using expressions for the average prevalence of susceptibility to infection and the incidence of infection during gestation. To estimate the number of cases of CRS, we assumed an overall risk of 65% after infection in the first 16 weeks of pregnancy and zero risk thereafter. These estimates were derived for each country for which data were available, then for each World Health Organization region, excluding Europe. RESULTS: The estimated mean incidence of CRS per 100,000 live births was lowest in the Eastern Mediterranean region (77.4, range 0-212) and highest in the Americas (175, range 0-598). The mean of the estimates of the total number of cases of CRS in developing countries in 1996 was approximately 110,000. The range was, however, very wide, from as few as 14,000 to as many as 308,000 cases. CONCLUSIONS: Congenital rubella syndrome is an under-recognized public health problem in many developing countries. There is an urgent need for collection of appropriate data to estimate the cost-effectiveness of a potential global rubella control programme.     

上海市麻疹、流行性腮腺炎、风疹抗体水平调查分析

[目的 ]　了解本市健康人群麻疹、腮腺炎、风疹的抗体水平。　 [方法 ]　采集 0～ 5 0岁健康人群血标本 5 43份 ,检测麻疹、腮腺炎、风疹抗体。　 [结果 ]　小于 8月龄组麻疹抗体GMT最低 ,接种麻疹疫苗后抗体GMT显著升高 (P<0 .0 0 1) ;小于 8月龄组及 8月龄组风疹抗体水平最低 ,1岁接种疫苗后风疹抗体显著升高 (P <0 .0 0 1) ,但随着年龄的增长抗体水平有所下降 ,抗体阳性率维持在 85 %以上 ;小于 8月龄组及 8月龄组流行性腮腺炎抗体水平最低 ,1岁以上各年龄组抗体水平显著上升 (P <0 .0 0 1)。　 [结论 ]　上海市现阶段实行麻疹疫苗、MMR疫苗的接种程序比较合理和有效 ,但应该进一步开展上海市育龄期妇女风疹抗体水平调查和MMR疫苗免疫持久性观察 ,研究预防未及龄儿童麻疹疫苗免疫策略、育龄期妇女接种风疹疫苗免疫策略 ,预防先天性风疹综合征     

Trends in early childhood vaccination coverage: Progress towards US Healthy People 2010 goals

Objectives

To evaluate trends in national vaccination coverage from 2000 to 2007 among children aged 19–35 months for at least four doses of diphtheria–tetanus–pertussis vaccine (4 + DTaP), three doses of poliovirus vaccine (3 + Polio), one dose of measles–mumps–rubella vaccine (1 + MMR), three doses of Haemophilus influenzae type b vaccine (3 + Hib), three doses of hepatitis B vaccine (3 + HepB), one dose of Varicella vaccine (1 + Var), and the standard vaccine series of these six vaccines (4:3:1:3:3:1). To predict vaccination coverage levels in 2008–2010 for those vaccines that have not yet reached the Healthy People 2010 coverage targets of 90% for individual vaccines and 80% for the vaccine series.

Methods

Data were analyzed for 167,086 children aged 19–35 months in the 2000–2007 National Immunization Survey. Vaccination coverage trends were analyzed with weighted least squares linear regression models. Nonlinear Weibull and logarithmic regression models were fitted to these past results, and extrapolation was used to predict vaccination coverage levels for 4 + DTaP, 1 + Var, and the 4:3:1:3:3:1 series from 2008 to 2010.

Results

From 2000 to 2007, observed vaccination coverage increased significantly for four of the six vaccines and the standard vaccine series, and reached the 90% target for 3 + Polio, 1 + MMR, 3 + Hib, and 3 + HepB. Increases in coverage were not significant for 1 + MMR and 3 + Hib; however, coverage for these vaccines was consistently > 90% throughout the study period. Both Weibull and logarithmic regression models predicted that coverage with 1 + Var and the 4:3:1:3:3:1 series will surpass the 2010 target by 2008, while coverage with 4 + DTaP will fall short of the target at 86% in 2010.

Conclusions

The United States is well on the way toward reaching most of the Healthy People 2010 objectives for early childhood vaccination coverage. Enhanced efforts are needed to ensure that these trends continue, and to increase coverage with 4 + DTaP.     

Safety profile of rubella vaccine administered to pregnant women: A systematic review of pregnancy related adverse events following immunisation,including congenital rubella syndrome and congenital rubella infection in the foetus or infant

BackgroundData on the safety of inadvertent rubella vaccination in pregnancy is important for rubella vaccination programs aimed at preventing congenital rubella syndrome.MethodsThe association between monovalent rubella or combination vaccinations in or shortly before pregnancy and potential harm to the foetus was examined by conducting a systematic review and meta-analysis using fixed effect methods and simulation.ResultsFour cohort studies of inadvertently vaccinated and unvaccinated women were found, 15 cohorts of pregnant women who were rubella susceptible at time of inadvertent vaccination and 9 cohort studies with no information on susceptibility and case series. No case of vaccine associated congenital rubella syndrome (CRS) was identified. Cohort studies with an unvaccinated comparison group were limited in number and size, and based on these only a theoretical additional risk of 6 or more cases of CRS per 1000 vaccinated women (0% observed, upper 95% CI 0.6%) could be excluded. Based on cohorts of vaccinated rubella susceptible pregnant women a maximum theoretical risk of 1 CRS case in 1008 vaccinated women (0% observed, upper 95% CI 0.099%) was estimated. Asymptomatic rubella vaccine virus infection of the neonate was also noted (fixed effects estimate of risk overall 1.74%, 95% CI 1.21, 2.28).ConclusionThere is no evidence that CRS is caused by rubella-containing vaccines but transplacental vaccine virus infection can occur. CRS is effectively prevented by vaccination, thus the risk/benefit balance is unequivocally in favour of vaccination. The data confirm previous recommendations that inadvertent vaccination during pregnancy is not an indication for termination of pregnancy.     

Elimination of rubella and congenital rubella syndrome--United States, 1969-2004

In October 2004, CDC convened an independent panel of internationally recognized authorities on public health, infectious disease, and immunization to assess progress toward elimination of rubella and congenital rubella syndrome (CRS) in the United States, a national health objective for 2010. Since rubella vaccine licensure in 1969, substantial declines in rubella and CRS have occurred, and the absence of endemic transmission in the United States is supported by recent data: 1) fewer than 25 reported rubella cases each year since 2001, 2) at least 95% vaccination coverage among school-aged children, 3) estimated 91% population immunity, 4) adequate surveillance to detect rubella outbreaks, and 5) a pattern of virus genotypes consistent with virus originating in other parts of the world. Given the available data, panel members concluded unanimously that rubella is no longer endemic in the United States. This report summarizes the history and accomplishments of the rubella vaccination program in the United States and the Western Hemisphere and the challenges posed by rubella for the future.     

Epidemiology of measles,mumps and rubella in Italy

A serosurvey for measles, mumps and rubella was conducted in Italy; incidence based on statutory notifications over the last three decades was also calculated. In Italy the diseases followed an endemic-epidemic pattern, with an incidence peak every 2-4 years, and had a limited reduction of incidence attributable to childhood immunization. Lower notification rates were observed in the Southern regions. This is possibly related to greater under notification in the South and is confirmed by our seroprevalence data. Incidence of measles and rubella and proportion of cases among young adults increased significantly in the three decades considered, but not for mumps. Serological data confirmed that these infections are still very frequent in Italy, without significant geographic variation in the country. In the age groups 2-4 and 5-9 years the percentage of individuals still susceptible to each virus was higher than 30%. The proportion of susceptible subjects older than 15 years was similar for the three infections (6.1, 11.7 and 8.8% for measles, mumps and rubella, respectively). The low vaccine coverage for rubella and measles in Italy has so far only partially affected the occurrence of the diseases. No impact of mumps vaccination is visible. The average number of deaths, for each disease, has decreased during the three study periods. Today the priority in Italy is to halt the progressive increase of the mean age of acquisition of the three infections, to eliminate differences in coverage among regions and to conform to European standards. This will be achieved through a combination of increasing MMR vaccine coverage before 2 years of age, implementing vaccination campaigns for low seroprevalence age groups, and/or introducing a second dose of MMR, depending on the level of current MMR coverage.     

Seroprevalence of measles,mumps and rubella among children in American Samoa, 2011, and progress towards West Pacific Region goals of elimination

Introduction

In line with the global goals for measles elimination, countries in the West Pacific Region (WPR) have set a goal to eliminate measles by 2012. Due to its contagiousness, high population immunity is needed for achieving and documenting measles elimination. We assessed population immunity to measles, mumps and rubella among first grade children in American Samoa (AS) through a seroprevalance study.

Methods

Using commercial indirect enzyme-linked immunosorbant IgG assays (Wampole Laboratories, Cranbury, NJ) we determined IgG antibodies against the measles, mumps, and rubella (MMR) viruses in sera collected from first grade students in AS in April–May 2011. Vaccination status was retrieved from the immunization cards. Factors associated with seropositivity of measles, mumps, and rubella were analyzed separately.

Result

Among 509 first grade students, measles, mumps, and rubella seroprevalence were 92%, 90%, and 93%, respectively. The proportions of first grade students with documented one or two doses of MMR vaccine were 93% and 84%, respectively. The vaccination status of 6% of the first graders was unknown and 1% was unvaccinated. Receiving two-doses of MMR vaccines was associated with high measles and mumps seropositivity (p < 0.01).

Conclusion

The high measles seroprevalence among children shows the progress by American Samoa towards measles elimination. Achieving and maintaining high two-dose MMR vaccine coverage in all age groups will aid in attaining the measles elimination status and prevent transmission of measles from potential imported measles cases from other countries.