Comparison of rubella seroepidemiology in 17 countries: progress towards international disease control targets

Rubella immunity among pregnant women and the burden of congenital rubella syndrome (CRS) in India, 2022

BACKGROUND

India aims to eliminate rubella and congenital rubella syndrome (CRS) by 2023. We conducted serosurveys among pregnant women to monitor the trend of rubella immunity and estimate the CRS burden in India following a nationwide measles and rubella vaccination campaign.

METHODS

We surveyed pregnant women at 13 sentinel sites across India from Aug to Oct 2022 to estimate seroprevalence of rubella IgG antibodies. Using age-specific seroprevalence data from serosurveys conducted during 2017/2019 (prior to and during the vaccination campaign) and 2022 surveys (after the vaccination campaign), we developed force of infection (FOI) models and estimated incidence and burden of CRS.

RESULTS

In 2022, rubella seroprevalence was 85.2% (95% CI: 84.0, 86.2). Among 10 sites which participated in both rounds of serosurveys, the seroprevalence was not different between the two periods (pooled prevalence during 2017/2019: 83.5%, 95% CI: 82.1, 84.8; prevalence during 2022: 85.1%, 95% CI: 83.8, 86.3). The estimated annual incidence of CRS during 2017/2019 in India was 218.3 (95% CI: 209.7, 226.5) per 100, 000 livebirths, resulting in 47,120 (95% CI: 45,260, 48,875) cases of CRS every year. After measles-rubella (MR) vaccination campaign, the estimated incidence of CRS declined to 5.3 (95% CI: 0, 21.2) per 100,000 livebirths, resulting in 1141 (95% CI: 0, 4,569) cases of CRS during the post MR-vaccination campaign period.

CONCLUSION

The incidence of CRS in India has substantially decreased following the nationwide MR vaccination campaign. About 15% of women in childbearing age in India lack immunity to rubella and hence susceptible to rubella infection. Since there are no routine rubella vaccination opportunities for this age group under the national immunization program, it is imperative to maintain high rates of rubella vaccination among children to prevent rubella virus exposure among women of childbearing age susceptible for rubella.

Identifying the population susceptible to rubella in Japan, 2020: Fine-scale risk mapping

BACKGROUND

Rubella remains a public health challenge in Japan, impeding the attainment of herd immunity. Despite vaccination efforts since 1976, persistent outbreaks reveal a susceptibility gap in male adults born before 1995. Seroepidemiological surveys are pivotal in evaluating population immunity and identifying at-risk groups.

METHODS

This study aims to pinpoint high-risk areas for potential rubella outbreaks in Japan by merging seroepidemiological data from 2020 with population census information. Various data sources, including spatial demographic data, reported rubella and congenital rubella syndrome (CRS) cases, and traveler lodging statistics, were employed. Geospatial information for Japan's 230,300 small geographic areas was analyzed, and HI (hemagglutination inhibition) titers were examined by age and sex. Seroconversion was defined as an HI titer ≥ 1:32 or 1:16, indicating protective immunity. Geospatial maps illustrated the distribution of susceptible individuals per square kilometer, emphasizing high-risk urban areas like Tokyo and Osaka. Demographic shifts in the working-age population were assessed.

RESULTS

Susceptible individuals cluster in densely populated urban centers, persisting despite demographic changes. The study highlights areas at risk of increased susceptibility, particularly with an HI titer cut-off of 1:16. Foreign travelers pose potential rubella importation risks as travel volume to Japan rises. To prevent epidemics and congenital rubella syndrome burden, achieving and sustaining herd immunity in high-risk areas is crucial.

CONCLUSIONS

This study offers a comprehensive assessment of vulnerability in densely populated Japanese regions. Integrating population statistics with seroepidemiological data enhances our understanding of population immunity, guiding resource allocation for supplementary vaccination planning. To avert rubella epidemics, high-risk locations must bolster indirect protection through herd immunity, ultimately preventing congenital rubella syndrome.

Seroprevalence of rubella virus infection among antenatal care clients of Halaba Town public health facilities, southern Ethiopia

Rubella virus infection during pregnancy has several effects on the developing fetus. However, little is known about the epidemiology of the infection in Ethiopia. A cross-sectional study was conducted to assess the seroprevalence of rubella virus infection on consecutive 299 pregnant women attending antenatal care clinics in public health facilities in Halaba Town, Southern Ethiopia. Structured questionnaires were used to collect information on socio-demographic and reproductive characteristics. Venous blood samples were collected, and sera were tested for anti-rubella IgM and IgG using the enzyme-linked immunosorbent assay. Anti-rubella IgG and IgM were detected in 265 (88.6%) and 15 (5.0%) of 299 participants, respectively. Pregnant women in their first trimester [crude odds ratio (cOR) = 4.26; 95% CI (1.47, 12.4)] were at increased risk of having anti-rubella IgM compared to those in their second and third trimesters. Urban residents [cOR = 4.06; 95% CI (1.94, 8.47)] were with a higher percentage of IgG positivity compared to rural residents. Anti-rubella IgG positivity was higher in housewives [cOR = 2.94; 95% CI (1.07, 8.04)] compared to self-employed women. Our findings showed a high prevalence of rubella virus exposure, and considerable percentages of recent infection and susceptible women to contracting the infection, emphasizing the importance of congenital rubella syndrome in the research area.

Rubella Humoral Immunity Among the Saudi Population of Madinah in the Western Region of Saudi Arabia

Maintaining herd immunity against the rubella virus is important for controlling the spread and recurrence of rubella. Rubella vaccination for children has been affordable in Saudi Arabia since 1982. To assess the immune response derived from vaccination, we assessed the seroprevalence against the rubella virus among the population of the Madinah region. An indirect enzyme-linked immunosorbent assay (ELISA) was used to measure anti-rubella IgG antibodies in 791 serum samples obtained from 336 (42.5%) men and 455 (57.5%) women, ranging from 14 to 49 years in age. Among all participants, 94.2% were seropositive for rubella IgG antibodies, indicating a high degree of immunization. However, 5.8% of participants were seronegative, suggesting a population of either poor vaccine responders or the potential risk of waning vaccine-induced immunity. No significant difference or association with rubella seropositivity was identified according to age, sex, or pregnancy status. The median anti-rubella IgG antibody concentrations differed significantly between age groups (p < 0.001). Although a high percentage of the tested population in Madinah demonstrated anti-rubella IgG antibody seropositivity, a notable percentage of the population were seronegative, making them susceptible to infection.

Parity status and the relationship between antenatal rubella serology with obstetric outcome

Routine antenatal rubella serological testing is adopted in many countries. In a population covered by universal childhood rubella immunization for four decades, we have observed an association between pre-eclampsia with maternal rubella seronegativity among multiparous gravidae. This retrospective cohort study was further performed to elucidate the interaction between parity status and rubella seronegativity on obstetric outcome in singleton pregnancies carried to ≥ 24 weeks gestation managed from 1997 to 2019, with the data retrieved from a computerized database used for annual statistics and auditing. Of the 133,926 singleton pregnancies eligible for the study, the 13,320 (9.9%) rubella seronegative gravidae had higher mean booking weight and body mass index (BMI), but shorter height, and higher incidence of advanced age (≥ 35 years), high BMI, short stature, and lower incidence of nulliparas. Univariate analysis showed that adverse obstetric outcomes were more frequently found among the multiparas. On multivariate analysis, there was increased postdated (> 41 weeks) pregnancy irrespective of parity status, while nulliparas had reduced gestational hypertension (aRR 0.714, 95% CI 0.567-0.899) and gestational diabetes (aRR 0.850, 95% CI 0.762-0.950), and multiparas had increased pre-eclampsia (aRR 1.261, 95% CI 1.005-1.582), neonatal death (aRR 2.796, 95% CI 1.243-6.291), and perinatal death (aRR 2.123, 95% CI 1.257-3.587). In conclusion, in a population covered by universal childhood rubella immunization, antenatal rubella seronegativity is associated with increased pre-eclampsia and perinatal loss only in multiparas, suggesting that the rubella seronegativity in these women served as proxy for some form of altered immune response which increases adverse pregnancy outcome.

The Screening of Rubella Virus, Cytomegalovirus, Hepatitis B Virus, and Toxoplasma gondii Antibodies in Prepregnancy and Reproductive-Age Women in Tabriz, Iran

OBJECTIVES

The organisms of Toxoplasma gondii, Rubella virus, Cytomegalovirus, and Herpes simplex virus as an acronym of TORCH are major pathogens in prepregnancy and reproductive-age women. These microorganisms are considered a serious problem and cause 2-3% of all birth defects in the fetus. Our study was aimed at screening the seroprevalence of TORCH antibodies among prepregnancy and reproductive-age women in Tabriz, Iran. Design and Setting. This study was carried out in 2726 prepregnancy and reproductive-age women, who were referred to the laboratory for prenatal TORCH screening. To detect the presence of IgG, IgM antibodies and Hepatitis B surface antigen against these microorganisms were carried out using a chemiluminescence immunoassay analyzer (CLIA).

RESULTS

In the current study, the rates of anti-Toxoplasma gondii IgG, anti-Rubella virus IgG, and anti-Cytomegalovirus IgG were found in 722 cases (26.5%), 2579 cases (94.6%0), and 2718 cases (99.7%), respectively. Moreover, the rates of anti-Toxoplasma gondii IgM, anti-Rubella virus IgM, and anti-Cytomegalovirus IgM were discovered in 10 cases (0.4%), 13 cases (0.5%), and 16 cases (0.6%), respectively. The Hepatitis B surface antigen was found in 32 cases (1.2%). The dissemination of positive TORCH in various ages was different (P < 0.05).

CONCLUSIONS

In our study, the seroprevalence of acute TORCH infections was relatively low. Due to the probability of vertical transmission to the fetus during pregnancy and the unpleasant complication of these pathogens, it is essential to be screened for detection of specific IgG and IgM antibodies in reproductive ages.

Prevalence of Rubella Antibodies among Fertile Women in the West of Romania, 18 Years after the Implementation of Immunization

Seronegative women are susceptible to primary rubella virus (RV) infection during pregnancy, which can cause fetal damage. Vaccination represents the main strategy in rubella prevention. The aim of this study was to analyze changes in the rubella seroprevalence and identify populations with a high susceptibility to RV. A cross-sectional study was performed on 6914 Caucasian fertile women who had Toxoplasma gondii, other viruses, Rubella, Cytomegalovirus, and the herpes simplex virus (TORCH) screening in two distinct periods-1452 at the Timișoara Municipal Hospital, Romania (Group 1: 2008-2010) and 5462 at the laboratory Bioclinica S.A., Timișoara, Romania (Group 2: 2015-2018). The RV seroprevalence decreased (Group 1 versus Group 2; 94.1% (92.7-95.2) versus 91.4% (90.6-92.1), OR = 0.76 (p = 0.0007)). According to the year of birth and eligibility to vaccination program, RV seroprevalence rates were 82.4% (76.8-86.8)/1997-2004, 85.4% (80.5-89.3)/1995-1996, 90.1% (89.0-91.1)/<1989, and 95.8% (94.7-96.6)/1989-1994. No significant difference in the RV seropositivity according to the place of residence was found. The overall RV susceptibility increased from 2008-2010 to 2015-2018. The highest susceptibility was found in women born between 1997-2004 eligible for measles-mumps-rubella (MMR) vaccine through the family practice system and the lowest in women born between 1989-1994 eligible for monovalent rubella vaccine conducted in schools.

Sero-prevalence of rubella among pregnant women in Sub-Saharan Africa: a meta-analysis

Background: Rubella continues to be a leading cause of vaccine-preventable congenital birth defects and permanent organ damage, especially in developing countries. For women who are infected with the rubella virus (RV) before conception or during the first trimester of pregnancy, the unborn child has up to a 90% probability of developing congenital rubella syndrome. There are limited data on the seroprevalence of the rubella virus among pregnant women in Sub-Saharan Africa. Therefore, the aim of this study was done to determine the pooled seroprevalence of rubella among pregnant women in Sub-Saharan Africa. Methods: The PRISMA guidelines protocol was followed to write the systematic review and meta-analysis. Published studies were searched in Medline, PubMed, Google scholar, advance google and Cochrane Library. The search terms on the databases are: "rubella"OR "rubeo*", "rubella"AND"seroepidemiology", "seroprevalen *" OR "prevalen*", "seroprevalen *" OR "seroimmun*", "rubella antibod*"AND "pregnan*", "seroprevalen *" AND "sub-Saharan Africa".The heterogeneity of studies was weighed using Cochran's Q test and I² test statistics. Publication bias was assessed by using Egger's and Begg's test. Results: Twenty-eight studies were included in this meta-analysis. The pooled seroprevalence of anti-RV IgG among pregnant women in Sub-Saharan African was 89.0% (95%CI: 84.6-92.3), and the pooled prevalence of anti-RV IgM among pregnant women in Sub-Saharan Africa was 5.1% (95%CI: 2.6-9.9). Conclusion: This meta-analysis showed that seronegativity and acute infection with RV among pregnant women in sub-Saharan Africa is high compared to other studies and the WHO threshold among women of child-bearing age. This finding calls for primary health care providers to make the community aware of this rubella-susceptible group and its healthcare burden, with the desired outcome that sub-Saharan Africa countries would introduce an implementation strategy for rubella vaccination of pregnant women and women of child-bearing age.

Seroepidemiological study of rubella in Vojvodina, Serbia: 24 years after the introduction of the MMR vaccine in the national immunization programme

Although rubella is usually a mild childhood disease, this infection in early pregnancy poses a serious problem due to its teratogenic effect. The goal of interrupted circulation and elimination of rubella virus was achieved in many countries in the world. The aim of this study was to determine the status of rubella immunity in Vojvodina and evaluate Serbia's progress toward this goal. A total of 3404 residual serum samples from patients of all ages (1 to 84 years) were included in the study. Samples were collected between May 2015 and December 2017 in Vojvodina. Rubella IgG antibodies were determined using an indirect chemiluminescent immunoassay. Percentage of participants seropositive for rubella antibodies was 92.9% in the entire sample. The highest number of seronegatives was in the youngest (1 year) age group (44.7%), followed by the group aged 24-49 (6.4%) and 2-11 years (6.2%). The absence of a higher percentage of children with protective anti-rubella antibodies in the group aged 2-11 can be explained by a lower immunization coverage during certain years. Participants in the group aged 24-49 were born during the pre-vaccination period with lower rubella incidence, leading to the conclusion that not all individuals of that age came into a contact with the virus. Comparing levels of anti-rubella IgG antibodies of seropositive males and females of different ages reveals that the immunity after a contact with the virus and a previously acquired infection is stronger than the immunity after the vaccination. Although the incidence rate of rubella in Vojvodina has been low for the last ten years, there is still a risk of an outbreak due to a decrease in immunization coverage. This study shows that the percentage of susceptible individuals is high, especially considering women aged 24-49, and that additional ("catch-up") immunization is required.

Recent trends in seroprevalence of rubella in Korean women of childbearing age: a cross-sectional study

OBJECTIVES

The aim of this study was to investigate the immunity against rubella using the serological status of rubella-specific IgG antibodies (antirubella IgG) in Korean women of childbearing age (15-49 years).

DESIGN

Retrospective cross-sectional study.

SETTING

Population-based cross-sectional study in South Korea.

PARTICIPANTS

Between January 2010 and December 2017, test results from Korean women aged 15-49 years who had visited an obstetric private clinic (nationwide institutions) and had requested rubella-specific IgG antibody tests from Green Cross Laboratories were obtained from the laboratory information system.

RESULTS

Between 2010 and 2017, antirubella IgG test results from 328 426 Korean women aged 15-49 years who had visited private obstetric clinics (1438 institutions nationwide) were retrospectively analysed by tested year, age, cohort and geographic regions. Over the 8-year study period, the rate of unimmunised women ranged from 7.8% to 9.7%. Multivariable-adjusted logistic regression models showed that the odds of being immune to rubella (positive and equivocal results of antirubella IgG test) were lower in 2017 compared with 2010, in women in their 40s, in a pre-catch-up cohort and in women living in Incheon, Busan, South Gyeongsang, North and South Jeolla and Jeju provinces (p<0.0001).

CONCLUSIONS

In consideration of the factors associated with prevalence of women unimmunised to rubella, future public health efforts should be focused on catch-up activities. The results of this study could be used to strengthen disease control and prevent rubella, including a nationwide immunisation programme.

Measles and rubella seroprevalence among adults in Georgia in 2015: helping guide the elimination efforts

A large-scale measles outbreak (11 495 reported cases, 60% aged ≥15 years) occurred in Georgia during 2013-2015. A nationwide, multistage, stratified cluster serosurvey for hepatitis B and C among persons aged ≥18 years conducted in Georgia in late 2015 provided an opportunity to assess measles and rubella (MR) susceptibility after the outbreak. Residual specimens from 3125 participants aged 18-50 years were tested for Immunoglobulin G antibodies against MR using ELISA. Nationwide, 6.3% (95% CI 4.9%-7.6%) of the surveyed population were seronegative for measles and 8.6% (95% CI 7.1%-10.1%) were seronegative for rubella. Measles susceptibility was highest among 18-24 year-olds (10.1%) and declined with age to 1.2% among 45-50 year-olds (P < 0.01). Susceptibility to rubella was highest among 25-29 year-olds (15.3%), followed by 18-24 year-olds (11.6%) and 30-34 year-olds (10.2%), and declined to <5% among persons aged ≥35 years (P < 0.001). The susceptibility profiles in the present serosurvey were consistent with the epidemiology of recent MR cases and the history of the immunization programme. Measles susceptibility levels >10% among 18-24 year-olds in Georgia revealed continued risk for outbreaks among young adults. High susceptibility to rubella among 18-34 year-olds indicates a continuing risk for congenital rubella cases.

The association of ToRCH infection and congenital malformations: A prospective study in China

OBJECTIVE

ToRCH infections (toxoplasmosis, rubella, cytomegalovirus and Herpes simplex virus) have long been known to be associated with bad obstetric outcomes. Little information is available about the impact of ToRCH infection on reproduction in china nearly for ten years. We designed a prospective study among 1863 pregnant women to investigate the association of ToRCH infection and congenital malformations.

STUDY DESIGN

All participants had set up a maternal health Handbook and were managed through the maternal and child health care system. They underwent regular pregnancy check-up, including physical measurements (weight, abdominal circumference and blood pressure), laboratory examinations (blood, urine) and ultrasound scan. ToRCH IgM antibodies were tested by chemiluminescence immunoassay.

RESULTS

102 participants were infected with ToRCH and the total infection rate was 6.06% (102/1683). CMV infection rate (3.15%, 53/1683) was the highest. The positive rate of ToRCH IgM antibodies increased significantly in participant with upper respiratory tract infection (14.6%, 32/219) or with adverse pregnancy history (4.8%, 70/1464). Among 85 ToRCH infected participants, adverse pregnancy outcome were observed in 57 cases which included abortions (31.8%, 27/85), premature births (8.2%, 7/85), congenital malformations (12.9%, 11/85), and stillbirths (9.4%, 8/85). Furthermore, congenital malformations was much higher than that in those without ToRCH infection (1.1%, 17/1598) (P＜0.001).

CONCLUSION

ToRCH infection was a significant risk factor of severe damage to the fetus, especially congenital malformations. ToRCH screening for pregnant women can reduce the incidence of adverse pregnancy and prevent birth defects in china.

The seroprevalence of cytomegalovirus infection in Belgium anno 2002 and 2006: a comparative analysis with hepatitis A virus seroprevalence

Cytomegalovirus (CMV) infection is endemic worldwide but its seroprevalence varies widely. The goal of this study was to estimate the age-specific seroprevalence of CMV infection in Belgium based on two cross-sectional serological datasets from 2002 and 2006. The seroprevalence was estimated relying on diagnostic test results based on cut-off values pre-specified by the manufacturers of the tests as well as relying on mixture models applied to continuous pathogen-specific immunoglobulin G antibody titre concentrations. The age-specific seroprevalence of hepatitis A virus (HAV), based on three Belgian cross-sectional serological datasets from 1993, 2002 and 2006, was used as a comparator since individuals acquire lifelong immunity upon recovery, implying an increasing seroprevalence with age. The age group weighted overall CMV seroprevalence derived from the mixture model was 32% (95% confidence interval (CI) 31-34%) in 2002 and 31% (95% CI 30-32%) in 2006. We demonstrated that CMV epidemiology differs from the immunizing infection HAV. This was the first large-scale study of CMV and HAV serial datasets in Belgium, estimating seroprevalence specified by age and birth cohort.

Impact of Maternal BMI on Rubella Nonimmunity at Antenatal Screening

OBJECTIVE

The aim of this study was to examine the relationship between BMI and the incidence of rubella nonimmunity among pregnant women with regard to the World Health Organization categories.

METHODS

This was a retrospective cohort study of 117,063 eligible gravidas, managed between 1998 and 2015 in a university hospital of Hong Kong, China. BMI at antenatal booking was banded using the following World Health Organization definitions: < 18.5 kg/m² , 18.5 to 24.9 kg/m² , 25.0 to 29.9 kg/m² , and ≥30.0 kg/m² . Maternal rubella nonimmunity status by BMI was assessed. Incidence rates were also assessed after adjusting for maternal advanced age, short stature < 151 cm, mothers' birthplace, and postobstetric history covariates.

RESULTS

Rubella nonimmunity incidence increased as the BMI increased (P < 0.001). Gravidas with high BMI were more likely to be nonimmune if born in Hong Kong (odds ratio [OR], 1.234; 95% CI: 1.159-1.315; P < 0.001) compared with those born outside of Hong Kong (OR, 1.066; 95% CI: 0.997-1.141; P = 0.063). After adjusting for covariates, women with BMI ≥ 25 kg/m² had 1.127 (P < 0.001; 95% CI: 1.074-1.182) greater odds of being nonimmune.

CONCLUSIONS

High maternal BMI (≥ 25.0 kg/m² ) is associated with reduced rubella immunity, an effect confined to gravidas with almost complete vaccine coverage in childhood.

Response to third rubella vaccine dose

Limited data exist on the immunogenicity of a third dose of the measles, mumps, and rubella vaccine (MMR). In this study, our aim was to evaluate the long-term rubella immunogenicity afforded by two childhood MMR doses of the Norwegian vaccination program in a cohort of conscripts and to determine the effect of an additional dose of MMR vaccine, in order to inform vaccination policy. Blood samples from Norwegian conscripts (n = 495) taken both before and eight months after administration of a dose of MMR vaccine were tested using an enzyme immunoassay to measure anti-rubella IgG. Concentrations <5 IU/mL were regarded as negative, 5.0-9.9 IU/mL as equivocal, and ≥10 IU/mL as positive. Overall, the seropositivity before vaccination was 84.6%, and 99.0% of the conscripts had anti-rubella IgG concentrations ≥5 IU/mL. The seropositivity after vaccination was 94.5%, and 99.8% of the conscripts had antibody concentrations ≥5 IU/mL. The geometrical mean IgG concentrations increased from 21.4 IU/mL before vaccination to 28.9 IU/mL after. Four out of five conscripts, with seronegative concentrations before administrations of an additional MMR dose, had equivocal or seropositive results following vaccination. The cohort of young adults in Norway, which was eligible for two childhood MMR doses, was protected against rubella, and efforts should be made to maintain high vaccine coverage to ensure immunity in the future. A third dose of MMR administered in early adulthood led to an increase in the antibody concentration in our cohort and seroconversion for the majority of seronegative persons.

Global seroprevalence of rubella among pregnant and childbearing age women: a meta-analysis

Background

We conducted a meta-analysis of articles published between January 2000 and July 2016 with the aim of defining the proportion of rubella seronegative women of childbearing age (WCBA), providing the best information available on the seroprevalence of rubella in this population. We selected articles published in the time period between 2000 and 2016. The pooled prevalence of rubella seronegative women was calculated by a fixed effect model and a random effect model, according to the heterogeneity among studies. Studies were sub-grouped by population type (pregnant women and WCBA with no mention of ongoing pregnancy) and by geographic area [World Health Organization (WHO) region]. Sensitivity analysis was performed to assess the stability of results. We found important differences in rubella seronegativity prevalence estimates by WHO Region. About 88% of the studies conducted on pregnant women reported a seronegativity rate >5%. The pooled rubella seronegativity prevalence was 9.3%. When considering population groups, we obtained a seronegativity pooled estimate of 9.4% for pregnant women and of 9.5% for WCBA with no mention of ongoing pregnancy. This meta-analysis shows that the proportion of WCBA who are susceptible to rubella is still high. The figures are worrisome, taking into account that the WHO set at 5% the rubella susceptibility threshold for WCBA.

Prior pregnancy and antenatal rubella sero-negativity-evidence of persistent maternal immunologic alteration?

PROBLEM

It is unclear if the immunologic alterations induced by pregnancy could persist.

METHOD OF STUDY

Antenatal rubella sero-negativity was correlated with gravidity, abortions and parity in 112 083 gravidae managed during 1997-2015, with further analysis stratified for factors known to influence rubella serology.

RESULTS

The 10.2% sero-negative gravidae had different characteristics, and the incidence showed significant difference and positive trend (P<.001 for both) with gravidity, abortions and parity. The pattern remained consistent when analysis was stratified for advanced age, high body mass index and medical history, but was negated by hepatitis B virus infection except for abortions, and by high body mass index for parity. For gravidity 2-4, no difference in rubella sero-negativity was found between gravidae with all previous pregnancies ended in abortion vs delivery.

CONCLUSION

Prior pregnancies diminished rubella immunity in a dose-dependent manner, which may be a reflection of the cumulative effect of pregnancy-associated maternal immunologic alteration.

Maternal rubella immunity status and pre-eclampsia

PROBLEM

To determine if maternal immune maladaptation associated with pre-eclampsia is reflected in the rubella immunity status.

METHOD OF STUDY

Incidence of pre-eclampsia was compared between rubella non-immune and immune gravidae carrying a singleton pregnancy beyond 24 weeks, taking into account maternal characteristics and reported risk factors for pre-eclampsia.

RESULTS

The 9870 (10.4%) rubella non-immune gravidae among the 95 024 in the cohort exhibited no difference in incidence of underlying medical disorders, but they were slightly but significantly older, shorter, heavier, and had more pre-eclampsia (OR 1.24, 95% CI 1.05-1.47) despite having fewer nulliparas. Regression analysis confirmed an overall association between rubella non-immunity with pre-eclampsia (aOR 1.27, 95% CI 1.06-1.54), which was related to multiparas (aOR 1.42, 95% CI 1.05-1.91) and carrying a male fetus (aOR 1.37, 95% CI 1.06-1.78).

CONCLUSION

The association between rubella non-immunity and pre-eclampsia reflects immune maladaptation in multiparas and toward a male fetus.

Mumps, measles and rubella vaccination in children with PFAPA syndrome

There is no published data regarding immunologic response to vaccinations in children with PFAPA syndrome (periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis). The aim of this study was to evaluate mumps, measles and rubella immunity in children with PFAPA. 31 children with PFAPA syndrome and 22 healthy children (control group - CG) were recruited to the study. All children were previously vaccinated with one dose of MMR vaccine according to the Polish obligatory vaccination schedule. The patients from both groups were evaluated for anti-measles, anti-mumps and anti-rubella IgG antibodies concentrations (ELISA tests; the reference values for protective antibody levels were 150IU/L, 16RU/L and 11IU/ml respectively). The percentage of patients with protective antibodies levels was as follows: measles - 93.55% of PFAPA and 95.45% of CG patients (p=0.77); mumps - 74.19% of PFAPA and 95.45% of CG patients (p=0.02); rubella - 80.65% of PFAPA and 90.9% of CG patients (p=0.30).

CONCLUSIONS

Children with PFAPA syndrome present a good response to the measles and rubella component of the MMR vaccine, however immunity against mumps after one dose of MMR may not be sufficient. Further investigation concerning immunity against vaccine-preventable diseases and the safety of vaccinations in children with periodic fever syndromes is required.

Rubella immune status of neonates - a window towards seroprevalence among childbearing women

BACKGROUND

When contracted in pregnancy, rubella may cause serious chronic infection of the fetus and development of Congenital Rubella Syndrome. Despite widespread application of rubella vaccination, periodical outbreaks are still being reported worldwide. The aim of this study was to determine rubella seroprevalence and antibody levels in neonates in Serbia as a proxy of maternal serostatus.

METHODS

ELISA based serological testing for rubella was done in 599 neonates treated at the Institute of Neonatology in Belgrade, from January 2010 to December 2011. All individuals with rubella IgG concentration ≥10 IU/ml were considered seropositive for rubella.

RESULTS

The mean age of enrolled neonates was 18 ± 6 days. The overall seroprevalence of rubella IgG antibodies among the tested neonates was 540/599(90.2 %, 95 % CI: 87.5-92.3). Seropositivity rate among sera of the neonates enrolled in 2010 was significantly higher than those collected in 2011 (p < 0.0001). There was no difference in average maternal age, gestational age or frequency of receiving blood products among the two study years. Significant high seropositivity rate was observed among neonates from mother aged >30 as compared to those from mothers aged <20 years (p = 0.02). Significant difference was also found between average IgG titers in the two study years (79 IU/mL in 2010 vs. 46 IU/mL in 2011, p < 0.0001).

CONCLUSION

We report on high rubella seroprevalence among newborns in Serbia, as a proxy of rubella serostatus of childbearing aged women. Notably, declining trend of rubella antibodies toward diminishing titers suggest the importance of sustained rubella serosurvey and antenatal screening at the national level.

Synthesis of Evidence to Characterize National Measles and Rubella Exposure and Immunization Histories

Population immunity depends on the dynamic levels of immunization coverage that countries achieve over time and any transmission of viruses that occur within the population that induce immunity. In the context of developing a dynamic transmission model for measles and rubella to support analyses of future immunization policy options, we assessed the model inputs required to reproduce past behavior and to provide some confidence about model performance at the national level. We reviewed the data available from the World Health Organization (WHO) and existing measles and rubella literature for evidence of historical reported routine and supplemental immunization activities and reported cases and outbreaks. We constructed model input profiles for 180 WHO member states and three other areas to support disease transmission model development and calibration. The profiles demonstrate the significant variability in immunization strategies used historically by regions and member states and the epidemiological implications of these historical choices. The profiles provide a historical perspective on measles and rubella immunization globally at the national level, and they may help immunization program managers identify existing immunity and/or knowledge gaps.

Systematic Review of Measles and Rubella Serology Studies

Serological tests provide information about individual immunity from historical infection or immunization. Cross-sectional serological studies provide data about the age- and sex-specific immunity levels for individuals in the studied population, and these data can provide a point of comparison for the results of transmission models. In the context of developing an integrated model for measles and rubella transmission, we reviewed the existing measles and rubella literature to identify the results of national serological studies that provided cross-sectional estimates of population immunity at the time of data collection. We systematically searched PubMed, the Science Citation Index, and references we identified from relevant articles published in English. We extracted serological data for comparison to transmission model outputs. For rubella, serological studies of women of child-bearing age provide information about the potential risks of infants born with congenital rubella syndrome. Serological studies also document the loss of maternal antibodies, which occurs at different rates for the different viruses and according to the nature of the induced immunity (i.e., infection or vaccine). The serological evidence remains limited for some areas, with studies from developed countries representing a disproportionate part of the evidence. The collection and review of serological evidence can help program managers identify immunity gaps in the population, which may help them better understand the characteristics of individuals within their populations who may participate in transmission and manage risks.

Seroepidemiology: an underused tool for designing and monitoring vaccination programmes in low- and middle-income countries

Seroepidemiology, the use of data on the prevalence of bio-markers of infection or vaccination, is a potentially powerful tool to understand the epidemiology of infection before vaccination and to monitor the effectiveness of vaccination programmes. Global and national burden of disease estimates for hepatitis B and rubella are based almost exclusively on serological data. Seroepidemiology has helped in the design of measles, poliomyelitis and rubella elimination programmes, by informing estimates of the required population immunity thresholds for elimination. It contributes to monitoring of these programmes by identifying population immunity gaps and evaluating the effectiveness of vaccination campaigns. Seroepidemiological data have also helped to identify contributing factors to resurgences of diphtheria, Haemophilus Influenzae type B and pertussis. When there is no confounding by antibodies induced by natural infection (as is the case for tetanus and hepatitis B vaccines), seroprevalence data provide a composite picture of vaccination coverage and effectiveness, although they cannot reliably indicate the number of doses of vaccine received. Despite these potential uses, technological, time and cost constraints have limited the widespread application of this tool in low-income countries. The use of venous blood samples makes it difficult to obtain high participation rates in surveys, but the performance of assays based on less invasive samples such as dried blood spots or oral fluid has varied greatly. Waning antibody levels after vaccination may mean that seroprevalence underestimates immunity. This, together with variation in assay sensitivity and specificity and the common need to take account of antibody induced by natural infection, means that relatively sophisticated statistical analysis of data is required. Nonetheless, advances in assays on minimally invasive samples may enhance the feasibility of including serology in large survey programmes in low-income countries. In this paper, we review the potential uses of seroepidemiology to improve vaccination policymaking and programme monitoring and discuss what is needed to broaden the use of this tool in low- and middle-income countries.

Seroprevalence of Antibodies against Measles, Rubella and Varicella among Asylum Seekers Arriving in Lower Saxony, Germany, November 2014-October 2015

The number of asylum seekers arriving in Germany has increased rapidly since 2014 and cases of vaccine-preventable diseases at reception centres were reported. Asylum seekers 12 years and older arriving in Lower Saxony were serologically screened for antibodies against measles, rubella and varicella between November 2014 and October 2015. We calculated the seroprevalence from the screening data by disease, country of origin and age group and compared them to literature-based herd immunity thresholds in order to identify immunisation gaps. In total, 23,647 specimens were included in our study. Although the vast majority of asylum seekers tested positive for antibodies against measles, rubella and varicella, the seroprevalences were not sufficient to ensure herd immunity. The seroprevalences varied substantially between countries of origin and increased with age. Immunisation of asylum seekers against measles, rubella and varicella is needed and the detailed information on seroprevalences among subgroups of asylum seekers can be used for targeted immunisations at reception centres.

Is birth cohort 1985/9-1990/8 a susceptibility window for congenital rubella syndrome in Taiwan?

OBJECTIVE

The worldwide prevalence of congenital rubella syndrome has drastically decreased after the uptake of vaccine to prevent the infection. However, outbreaks have occurred in some countries due to their own vaccination policies, and this phenomenon has not yet been investigated in Taiwan. Our study aims to fill this gap.

MATERIALS AND METHODS

We constructed an analytical database containing 10,824 pregnant women at the Taipei City Hospital, Taipei, Taiwan from January 2004 to July 2012. They were categorized into five birth cohorts according to the different vaccination programs in Taiwan: those born before 1971; those born between September 1971 and August 1976; between September 1976 and August 1979; between September 1979 and August 1985; and between September 1985 and August 1990. Differences of the seronegative rate and titers were compared using the Chi-square and Kruskal-Wallis tests among the five cohorts.

RESULTS

The seronegative rates for the five cohorts were 15.00%, 4.07%, 2.88%, 4.21%, and 10.98%, respectively, and were statistically significant different (p < 0.001). The first and fifth cohorts were higher than the average of seronegativity (5%). The mean of log transformed titers were 3.69 IU/mL, 4.22 IU/mL, 4.22 IU/mL, 4.05 IU/mL, and 3.44 IU/mL, which were statistically significant different (p<0.001). Our study also found that the equivocal rates (7.58%) were the highest in the cohort born between September 1985 and August 1990, among those who had been vaccinated. Our study showed that women younger than 27 years had a lower geometric mean titer of antibody titer than the average (60.60 IU/mL).

CONCLUSION

The previous vaccination policy in Taiwan has created a susceptibility window for rubella and congenital rubella syndrome over the past decades. We recommend having the antibody test before pregnancy for women born between September 1985 and August 1990, and implement a catch-up vaccine for those who were either seronegative or equivocal to prevent reinfection during their childbearing period.

Serological statuses of pregnant women in an urban Brazilian population before and after the 2008 rubella immunization campaign

BACKGROUND

Vaccinating populations against rubella aims to mitigate viral circulation and to ensure that women of childbearing age are immunized to reduce the incidence of congenital rubella syndrome. This study determined the serological statuses of pregnant women in an urban Brazilian population before and after the national rubella immunization campaign that was undertaken in 2008, and it assessed the socio-demographic factors associated with seronegativity.

METHODS

Pregnant women living in Maceió, Alagoas, Brazil, who participated in a municipal prenatal screening program that involved blood tests for rubella, were assessed between June 2007 and May 2012. Socio-demographic factors associated with seronegativity were assessed, including the year of the blood test, categorized as before or after the 2008 immunization campaign, and the women's birth cohorts, the women's ethnicities, the gestational ages at the first prenatal visit, and the women's districts of residence.

RESULTS

A total of 54,717 capillary blood samples were tested for rubella. The prevalence of pregnant women who were seronegative for rubella declined from 9.4% before the national immunization campaign to 2.8% after the national immunization campaign. Women were more likely to be seronegative for rubella before and after the immunization campaign if they were born between 1990 and 2000 or delayed starting prenatal care.

CONCLUSIONS

The decline in the prevalence of pregnant women who were seronegative for rubella to <5% indicates that the 2008 Brazilian rubella immunization campaign was successful in Maceió.

Post-exposure passive immunisation for preventing rubella and congenital rubella syndrome

BACKGROUND

Control of rubella is desired because infection in early pregnancy can result in miscarriage, foetal death or congenital abnormality. Primary studies examining the effectiveness of immunoglobulins for post-exposure prophylaxis of rubella have small sample sizes and varying results. National public health recommendations suggest a degree of effectiveness.

OBJECTIVES

To assess the effectiveness of intramuscular injection or intravenous infusion of polyclonal immunoglobulins of human sera or plasma origin for preventing rubella and congenital rubella syndrome when administered to exposed susceptible people before the onset of disease.

SEARCH METHODS

We searched CENTRAL (2014, Issue 7), MEDLINE (1946 to August week 2, 2014), EMBASE (1974 to August 2014), CINAHL (1981 to August 2014), LILACS (1982 to August 2014) and Web of Science (1955 to August 2014). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry on 16 October 2014. We searched the reference lists of relevant retrieved reviews and studies and identified national public health guidelines.

SELECTION CRITERIA

For the outcome 'preventing cases of rubella', we included randomised controlled trials (RCTs) and quasi-RCTs. We found several studies addressing this outcome where the design was a controlled clinical trial (CCT) (with exposure to rubella virus controlled by the investigators) but the method of allocation of participants to groups was not reported. We found an alternative report of one of these studies that indicated participants were assigned to groups randomly. We therefore included such studies as meeting criteria for RCTs or quasi-RCTs and undertook sensitivity analyses. For the outcomes, 'congenital rubella infection' and 'congenital rubella syndrome', we included RCTs, quasi-RCTs and prospective controlled (cohort) studies. Participants were necessarily susceptible and exposed to rubella. Polyclonal immunoglobulins derived from human sera or plasma must have been administered intramuscularly or intravenously as the only intervention in at least one group.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included 12 studies (430 participants) in the review: seven RCTs and five CCTs where it was not clear whether participants were randomly allocated to groups. We did not include any unpublished studies. Participants included children and adults of both sexes. Only one study included pregnant women. All studies were conducted in high-income countries.The quality of the 11 studies in the initial meta-analysis was moderate, although we classified no study as having a low risk of bias on all criteria.We included 11 studies in the initial meta-analysis of gamma-globulin (concentrated polyclonal immunoglobulins) versus control (saline or no treatment) for rubella cases. The result favoured the intervention group (risk ratio (RR) 0.61, 95% confidence interval (CI) 0.45 to 0.83) but was heterogenous (Chi² test = 36.59, df = 10 (P value < 0.0001); I² statistic = 73%). Heterogeneity was explained by subgrouping studies according to the estimated volume of gamma-globulin administered per pound of bodyweight and then removing those studies where the intervention was administered more than five days after participant exposure to rubella (post hoc analysis). The test of subgroup differences demonstrated heterogeneity between subgroups according to our protocol definition (P value < 0.1; I² statistic > 60%) and there appeared to be greater effectiveness of the intervention when a greater volume of gamma-globulin was administered ('0.027 to 0.037 ml/lb' RR 1.60 (95% CI 0.57 to 4.52); '0.1 to 0.15 ml/lb' RR 0.53 (95% CI 0.29 to 0.99); '0.2 to 0.5 ml/lb' RR 0.20 (95% CI 0.04 to 1.00)).None of the studies reported the outcome 'congenital rubella infection'. One included study reported on congenital rubella syndrome, with no cases among participants who were fewer than nine weeks pregnant at enrolment and who were randomised to one of two gamma-globulin groups ('high' or 'low' rubella titre). However, the study did not report how congenital rubella syndrome was measured and did not report the length of follow-up according to intervention group. This study did not include a non-treatment group.No included study measured adverse events.

AUTHORS' CONCLUSIONS

Compared to no treatment, polyclonal immunoglobulins seem to be of benefit for preventing rubella. The available evidence suggests that this intervention may be of benefit up to five days after exposure, and that effectiveness is dependent on dose. Considering the attack rate for rubella cases in the control group of the highest volume gamma-globulin subgroup (333 per 1000), the absolute risk reduction (calculated from the RR) for this volume of gamma-globulin was 266 (95% CI 0 to 320) and the number needed to treat to benefit is four (95% CI 3 to incalculable).The included studies did not measure rubella-specific antibodies in the immunoglobulin products used in a standard way and thus estimation of the dose of rubella-specific antibodies in international units administered was not possible. As the concentration of rubella-specific antibodies in today's polyclonal immunoglobulin products may vary from those products used in the studies in the review, the volume required per pound of bodyweight to produce similar results may also vary.There is insufficient evidence to make direct conclusions about the effectiveness of polyclonal immunoglobulins for preventing congenital rubella syndrome. This is an area requiring further research.

Rubella seronegativity in antenatal screening - Is it influenced by the introduction of universal childhood rubella immunization?

OBJECTIVE

This study examined the impact of rubella immunization, implemented in Hong Kong in phases since 1978, on antenatal rubella serological status in Chinese women.

METHODS

In a retrospective cohort study, the incidence of antenatal rubella seronegative status in our parturients managed from 1998 to 2013 was analyzed by their year-of-birth as follows: <1965 (no childhood immunization), 1965-1982 (single dose at Primary 6), and ≥1983 (two doses at age 12 months and 12 years), adjusting for other factors including age, parity, body mass index, place-of-birth status and hepatitis B surface antigen (HBsAg) status.

FINDINGS

Rubella seronegativity decreased from 12.9%, 10.5%, to 9.8% respectively, and correlated inversely (P<0.001) with year-of-birth cohorts. Despite similar demographic profiles, this correlation was found only in Hong-Kong-born women (from 12.6%, 7.5% to 6.5% respectively), who also had significant lower incidences of rubella seronegativity (OR 0.73, 0.31 and 0.29 respectively) and HBsAg seropositivity (OR 1.09, 0.63 and 0.48 respectively) than China-born women. On regression analysis, rubella seronegativity was actually significantly increased following the implementation of immunization (aOR 1.20) while it was the reverse for non-residents (aOR 0.61).

CONCLUSION

Although rubella seronegativity decreased with immunization, the effect was less than expected when adjusted for other risk factors.

Rubella outbreak in a Rural Kenyan District, 2014: documenting the need for routine rubella immunization in Kenya

Background

Rubella infection has been identified as a leading cause of birth defects commonly known as Congenital Rubella Syndrome (CRS). Kenya does not currently have a rubella immunization program nor a CRS surveillance system. In 2014, a rubella outbreak was reported in a rural district in Kenya. We investigated the outbreak to determine its magnitude and describe the outbreak in time, place and person. We also analyzed the laboratory-confirmed rubella cases from 2010 to 2014 to understand the burden of the disease in the country.

Methods

The Rubella outbreak was detected using the case-based measles surveillance system. A suspected case was a person with generalized rash and fever while a confirmed case was a person who tested positive for rubella IgM. All laboratory-confirmed and epidemiologically linked cases were line listed. The measles case-based surveillance database was used to identify rubella cases from 2010 to 2014.

Results

A total of 125 rubella cases were line listed. Fifty four percent of cases were female. Case age ranged from 3 months to 32 years with a median of 4 years. Fifty-one percent were aged less than 5 years, while 82 % were aged less than 10 years. Six percent of the cases were women of reproductive age. All cases were treated as outpatients and there were no deaths. The number of confirmed rubella cases was 473 in 2010, 604 in 2011, 300 in 2012, 336 in 2013 and 646 in 2014.

Conclusions

Analysis of Kenya rubella data shows that rubella is endemic throughout the country, and many outbreaks may be underestimated or undocumented. Six percent of all the cases in this outbreak were women of reproductive age indicating that the threat of CRS is real. The country should consider initiating a CRS surveillance system to quantify the burden with the goal of introducing rubella vaccine in the future.

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

OBJECTIVE

In 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).

METHODS

Epidemiological 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.

FINDINGS

The 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.

CONCLUSION

All 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.

Estimating seroprevalence of vaccine-preventable infections: is it worth standardizing the serological outcomes to adjust for different assays and laboratories?

The aim of the European Sero-Epidemiology Network 2 (ESEN2) project was to estimate age-specific seroprevalence for a number of vaccine-preventable diseases in Europe. To achieve this serosurveys were collected by 22 national laboratories. To adjust for a variety of laboratory methods and assays, all quantitative results were transformed to a reference laboratory's units and were then classified as positive or negative to obtain age-specific seroprevalence. The aim of this study was to assess the value of standardization by comparing the crude and standardized seroprevalence estimates. Seroprevalence was estimated for measles, mumps, rubella, diphtheria, varicella zoster and hepatitis A virus (HAV) and compared before and after serological results had been standardized. The results showed that if no such adjustment had taken place, seroprevalence would have differed by an average of 3·2% (95% bootstrap interval 2·9-3·6) although this percentage varied substantially by antigen. These differences were as high as 16% for some serosurveys (HAV) which means that standardization could have a considerable impact on seroprevalence estimates and should be considered when comparing serosurveys performed in different laboratories using different assay methods.

Rubella immunity in women of childbearing age, eight years after the immunization program in iran

Background:

Rubella is a viral disease with a worldwide distribution. Mass vaccination campaigns have increased the vaccine coverage in the world with substantial impact on reduction of rubella infections. In Iran, the national measles-rubella campaign, targeting individuals 5-25 years old, was initiated in 2003 and mass childhood vaccination against measles, rubella and mumps has continued ever since.

Objectives:

The aim of this study was to evaluate the efficacy of routine vaccination on rubella immunity among women of childbearing age in Babol, north of Iran.

Patients and Methods:

This cross-sectional study was conducted on 812 women of childbearing age living in Babol, north of Iran, in 2011. Twelve samples were excluded from the study because of inadequate sera amounts. Serum samples were examined for presence of rubella-specific IgG antibodies by means of quantitative ELISA.

Results:

From a total of 800 samples in this study, rubella IgG seropositivity was seen in 786 (98.3% [95% CI = %97.5-%99.1]) cases. The maximum IgG seropositivity (99.2%) was seen in the age group of 21-25 years old and the lowest immunity (87.7%) was in the group of above 30 years old.

Conclusions:

Our data indicated that the rate of seropositivity to rubella virus in our population was high, suggesting that vaccination has been successful in Babol, reducing the likelihood of congenital rubella infection.

Is the current prevention strategy based on vaccination coverage and epidemiological surveillance sufficient to achieve measles and rubella elimination in Europe?

Elimination of measles and rubella in Europe is a feasible objective, but it requires achieving a maintaining a high prevalence of protected individuals in order to prevent cases and outbreaks from imported cases. The epidemiology of measles and rubella in Europe in the period 2003-2013 suggests that we are far away from the elimination target for measles, while the situation is better for rubella. In this situation, a new preventive strategy based on serological surveillance systems should be developed in Europe in order to identify and immunise individuals in population groups without sufficient herd immunity against measles and rubella.

[Long effect of a booster on rubella antibodies from each original HI titer following vaccination]

This study was performed to clarify which titers of a pre-existing antibody could be efficiently boosted by vaccination and to assess the persistence of the antibodies. Two hundred healthy volunteer students with HI antibody titers of < or = 1:32 were enrolled. There were 6-16% of subjects with the negative HI antibody who had B-cell memory against rubella, because the EIA-IgM antibody remained negative and/or the avidity of the EIA-IgG antibody was high after vaccination. Furthermore most of them had already been vaccinated just once before. The ratio of those in whom the antibody levels increased significantly at one month after vaccination were 98%, 87%, 67% and 32% in subjects with an HI antibody titer of <1:8, < or =1: 8, < or =1:16 and < or =1:32 at pre-vaccination, respectively. The titers decreased significantly at two years after vaccination, however the ratio of decrease under each original level being 4%, 21.9%, 42.6% and 73.5% in each group of <1:8, < or =1: 8, < or =1:16 and < or = 1: 32, respectively. In comparison with the numbers of the subjects with <1: 8, the ones with < or = 1: 8, < or = 1:16 and < or = 1:32 increased 1.5-, 2.5- and 4.7-fold, respectively. Therefore, the recommendation of an HI antibody titer < or = 1:16 for vaccination in Japan is thought to be loose, although this is to decrease the risk of congenital rubella syndrome. We think that a new assay for cellular immunity for rubella should be developed in the future in order to ascertain whether congenital rubella syndrome will be prevented or not.

Underreporting of viral encephalitis and viral meningitis, Ireland, 2005-2008

Viral encephalitis (VE) and viral meningitis (VM) have been notifiable infectious diseases under surveillance in the Republic of Ireland since 1981. Laboratories have reported confirmed cases by detection of viral nucleic acid in cerebrospinal fluid since 2004. To determine the prevalence of these diseases in Ireland during 2005–2008, we analyzed 3 data sources: Hospital In-patient Enquiry data (from hospitalized following patients discharge) accessed through Health Intelligence Ireland, laboratory confirmations from the National Virus Reference Laboratory, and events from the Computerised Infectious Disease Reporting surveillance system. We found that the national surveillance system underestimates the incidence of these diseases in Ireland with a 10-fold higher VE hospitalization rate and 3-fold higher VM hospitalization rate than the reporting rate. Herpesviruses were responsible for most specified VE and enteroviruses for most specified VM from all 3 sources. Recommendations from this study have been implemented to improve the surveillance of these diseases in Ireland.

Seroprevalence of antibodies against measles, rubella, mumps, varicella-zoster, and B. Pertussis in young adults of Madrid, Spain

In recent years, there has been an increase in the number of cases of certain immunopreventable diseases in our country. A high proportion of these have been recorded among the young adult population. The aim of this study was to determine the seroprevalence of antibodies against immunopreventable diseases with the greatest health impacts on the young adult population (19-39 y of age) in Madrid. We collected a total of 1,153 serum samples from healthy volunteers undergoing routine medical visits and used ELISA to determine the presence of IgG antibodies against measles, rubella, mumps, and varicella zoster, as well as Bordetella pertussis. The Pearson's χ(2) test was used to compare prevalences, the Mann-Whitney U test was used to compare means, and the Kruskal-Wallis test was applied for variables with more than 2 categories. Statistical significance was achieved with p values of<0.05. The global prevalence of antibodies was 92.1% for measles, 94.4% for rubella, 88.3% for mumps, 92.8% for varicella zoster, and 70.2% for B. pertussis. No statistically significant differences were found between genders. The prevalence of antibodies against measles was more than 95% in the group of individuals born after 1986, and the percentage of individuals susceptible to rubella was less than 5% in women born after 1986. In spite of adequate vaccination coverage, in our region, a population of young adults exists who have not achieved the objectives of the WHO for the elimination of measles and congenital rubella syndrome.

How useful is a history of rubella vaccination for determination of disease susceptibility? A cross-sectional study at a public funded health clinic in Malaysia

BACKGROUND

Identification of pregnant women susceptible to rubella is important as vaccination can be given postpartum to prevent future risks of congenital rubella syndrome. However, in Malaysia, rubella antibody screening is not offered routinely to pregnant women in public funded health clinics due to cost constraint. Instead, a history of rubella vaccination is asked to be provided to establish the women's risk for rubella infection. The usefulness of this history, however, is not established. Thus, this paper aimed to determine the usefulness of a history of rubella vaccination in determining rubella susceptibility in pregnant women.

METHODS

A cross-sectional study was conducted on 500 pregnant women attending a public funded health clinic. Face-to-face interviews were conducted, and demographic data and history of rubella vaccination were obtained. Anti-rubella IgG test was performed.

RESULTS

A majority of the women (66.6%) had a positive vaccination history. Of these, 92.2% women were immune. A third (33.4%) of the women had a negative or unknown vaccination history, but 81.4% of them were immune to rubella. The sensitivity and specificity of a history of rubella vaccination in identifying disease susceptibility was 54.4% (95% CI: 40.7, 67.4%) and 69.3% (95% CI: 64.7, 73.5%) respectively; the positive predictive value was 18.6% (95% CI: 13.1, 25.5%) and the negative predictive value was 92.2% (95% CI: 88.6, 94.7%).

CONCLUSIONS

A vaccination history of rubella had a poor diagnostic value in predicting rubella susceptibility. However, obtaining a vaccination history is inexpensive compared with performing a serological test. A cost-utility analysis would be useful in determining which test (history versus serological test) is more cost-effective in a country with resource constraint.

Immunity to tetanus and diphtheria in the UK in 2009

INTRODUCTION

This study aimed to estimate the immunity of the UK population to tetanus and diphtheria, including the potential impact of new glycoconjugatate vaccines, and the addition of diphtheria to the school leaver booster in 1994.

METHODS

Residual sera (n=2697) collected in England in 2009/10 were selected from 18 age groups and tested for tetanus and diphtheria antibody. Results were standardised by testing a panel of sera (n=150) to enable comparison with a previously (1996) published serosurvey. Data were then standardised to the UK population.

RESULTS

In 2009, 83% of the UK population were protected (≥0.1 IU/mL) against tetanus compared to 76% in 1996 (p=0.079), and 75% had at least basic protection against diphtheria (≥0.01 IU/mL) in 2009 compared to 60% in 1996 (p<0.001). Higher antibody levels were observed in those aged 1-3 years in 2009 compared to 1996 for both tetanus and diphtheria. Higher diphtheria immunity was observed in those aged 16-34 years in 2009 compared to 1996 (geometric mean concentration [GMC] 0.15 IU/mL vs. 0.03 IU/mL, p<0.001). Age groups with the largest proportion of susceptible individuals to both tetanus and diphtheria in 2009 were <1 year old (>29% susceptible), 45-69 years (>20% susceptible) and 70+ years (>32% susceptible). Low immunity was observed in those aged 10-11 years (>19% susceptible), between the scheduled preschool and school leaver booster administration.

DISCUSSION

The current schedule appears to induce protective levels; increases in the proportions protected/GMCs were observed for the ages receiving vaccinations according to UK policy. Glycoconjugate vaccines appear to have increased immunity, in particular for diphtheria, in preschool age groups. Diphtheria immunity in teenagers and young adults has increased as a result of the addition of diphtheria to the school leaver booster. However, currently older adults remain susceptible, without any further opportunities for immunisations planned according to the present schedule.

Prevalence of antibodies against measles, mumps and rubella in the childhood population in Singapore, 2008-2010

We undertook a national paediatric seroprevalence survey of measles, mumps and rubella (MMR) in Singapore to assess the impact of the national childhood immunization programme against these three diseases after introduction of the trivalent MMR vaccine in 1990. The survey involved 1200 residual sera of Singapore residents aged 1-17 years collected from two hospitals between 2008 and 2010. The overall prevalence of antibodies against measles, mumps and rubella was 83∙1% [95% confidence interval (CI) 80∙9-85∙1], 71.8% (95% CI 69∙1-74∙2) and 88∙5% (95% CI 86∙6-90∙2), respectively. For all three diseases, the lowest prevalence was in children aged 1 year (47∙8-62∙3%). The seroprevalence of the vaccinated children declined over time. The national MMR immunization programme is effective in raising the herd immunity of the childhood population, although certain age groups are more susceptible to infection, in particular, those who are not eligible for vaccination at age <15 months.

Seroepidemiology of mumps in Europe (1996-2008): why do outbreaks occur in highly vaccinated populations?

Mumps outbreaks have recently been recorded in a number of highly vaccinated populations. We related seroprevalence, epidemiological and vaccination data from 18 European countries participating in The European Sero-Epidemiology Network (ESEN) to their risk of mumps outbreaks in order to inform vaccination strategies. Samples from national population serum banks were collected, tested for mumps IgG antibodies and standardized for international comparisons. A comparative analysis between countries was undertaken using age-specific mumps seroprevalence data and information on reported mumps incidence, vaccine strains, vaccination programmes and vaccine coverage 5-12 years after sera collection. Mean geometric mumps antibody titres were lower in mumps outbreak countries [odds ratio (OR) 0·09, 95% confidence interval (CI) 0·01-0·71)]. MMR1 vaccine coverage ⩾95% remained protective in a multivariable model (P < 0·001), as did an interval of 4-8 years between doses (OR 0·08, 95% CI 0·01-0·85). Preventing outbreaks and controlling mumps probably requires several elements, including high-coverage vaccination programmes with MMR vaccine with 4-8 years between doses.

Persistence and titer changes of rubella virus antibodies in primiparous women who had been vaccinated with strain RA 27/3 in junior high school

Taiwan's rubella vaccination program was launched in 1986; each schoolgirl in the third grade of junior high school received one dose of rubella (RA 27/3) vaccine. We reviewed the results of 14,090 prenatal rubella tests for primiparas from three areas of Taiwan during 2002 to 2008 to investigate seronegativity rates and titer changes. In all primiparous women, the average rubella virus seronegativity rate was 6.5% (95% confidence interval [95% CI], 6.1 to 6.9%), and the average rubella virus antibody titer was 65.9 IU/ml (95% CI, 64.7 to 67.1 IU/ml). There were 1,220 women (8.7%) with weakly positive antibody titers (10 to 20 IU/ml). The rubella virus seronegativity rates, which ranged from 5.4 to 9.7%, did not exhibit a linear trend from 9 to 22 years after vaccination (P = 0.201); in contrast, a significant trend appeared in the average rubella virus IgG titer (P = 0.003), dropping from 69.9 IU/ml in the 9th year after vaccination to 54.8 IU/ml in the 22nd year. The mean annual antibody decay rate was -0.77 IU/ml. This study reveals that the level of rubella virus antibodies declined slowly in women of childbearing age who were vaccinated with RA 27/3 at junior high school age. The number of women who were seronegative or had weakly positive antibody titers was still high (15.2%). Therefore, in countries that implement a single-dose regimen in children or teenagers, it should remain an important policy to encourage voluntary immunization in seronegative women and to immunize all postpartum women who are susceptible to rubella virus infection before they leave the hospital.

Rubella revisited: where are we on the road to disease elimination in Central Europe?

Rubella is a contagious viral disease with few complications except when contracted by pregnant women. Rubella infection in pregnancy can result in miscarriage, stillbirth or an infant born with congenital rubella syndrome (CRS) which comprises deafness, heart disease, cataracts and other permanent congenital manifestations. Clinical diagnosis of rubella is difficult due to overlapping symptoms with many other diseases and confirmation of rubella is not possible without laboratory testing. Effective vaccination programmes are critical to the elimination of rubella and prevention of CRS. Such programmes have been successful in several countries in Europe and around the world. However, rubella outbreaks still occur due to suboptimal vaccine coverage and in the past 10 years rubella has been reported in Central European countries such as Romania and Poland. Over the past decade the elimination of rubella and prevention of congenital rubella infection in Europe has been a high priority for the WHO European Regional Office. In 2010 the WHO regional committee for Europe renewed its commitment to the elimination of rubella and prevention of CRS with a new target of 2015. This paper examines the current situation for rubella and CRS in Central Europe and describes the different rubella vaccination programmes in the region. The Central European Vaccination Advisory Group (CEVAG) recommends that two doses of measles, mumps and rubella vaccine, MMR, should be given to all children. The first dose should be given between 12 and 15 months of age. The second dose can be given between the ages of 21 months and 13 years with the exact age of administration of the second dose depending on the situation specific to each country. All suspected rubella cases should be laboratory-confirmed and monitoring systems to detect and investigate cases of CRS should be strengthened.

Rubella seroepidemiology and estimations of the catch-up immunisation rate and persistence of antibody titers in pregnant women in Taiwan

OBJECTIVE

To examine rubella seroepidemiology, and estimate rates of catch-up immunisation and persistence of antibody titers in pregnant women in Taiwan after mass immunisation.

DESIGN

A retrospective study.

SETTING

Two medical centres and four regional hospitals specialising in obstetric care.

SAMPLE

A total of 43,640 prenatal rubella test results for pregnant women from 2001 to 2008.

METHODS

Rubella immunoglobulin G (IgG) antibody assay.

MAIN OUTCOME MEASURES

Seronegativity, rate of catch-up immunization, and antibody decline.

RESULTS

The seronegativity was 10.9% in all pregnant women. Immigrant women had higher seronegativity than indigenous women (OR 2.86; 95% CI 2.65, 3.01). Indigenous women born prior to implementation of the vaccination programmes were more susceptible (20.1%) to rubella infection than were women born thereafter (6.7%). Rates of seropositive conversion were low in both Taiwanese-born and foreign-born women (11.5 and 30.7%, respectively). The rubella antibody titers for vaccinated Taiwanese women in the 1971-1976 and after-1976 birth cohorts declined by 0.6 and 2.3% per year, respectively.

CONCLUSIONS

This study demonstrates high seronegativity of older indigenous and immigrant women, a low catch-up immunisation rate, and the persistence of rubella antibodies in Taiwan after mass vaccination. Our study suggests that a single dose of rubella vaccine in teenagers effectively increased rubella seropositivity during their childbearing years. This finding is useful for countries that lack the resources necessary for a two-dose regimen. We recommend free rubella antibody tests to women of childbearing age and free vaccination as required. All postpartum women testing negative for rubella antibodies should be vaccinated before they leave hospital.