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.     

芜湖市妊娠期妇女风疹抗体的血清学研究

目的了解芜湖市妊娠期妇女风疹抗体情况。方法通过调查问卷收集调查对象的有关信息,使用ELISA方法对样本中风疹IgG抗体进行检测。结果本研究显示风疹自然感染率达到74.29%,同时,风疹疫苗接种率极低;单因素分析显示,不同教育水平,经济收入及年龄,妊娠期妇女的抗体阳性率无明显差异。结论风疹的自然感染率较高,而风疹疫苗接种率极低,因此采取相应的预防措施与实施育龄期妇女风疹疫苗的接种十分必要。     

Seroprevalence of rubella in female migrant factory workers in Shenzhen, China

Background

Rubella remains a common disease in Mainland China and is a major cause of severe birth defects from Congenital Rubella Syndrome (CRS). Rubella-containing vaccines were not included in China's National Expanded Program of Immunization (NEPI) until December 2007. In Shenzhen, women of childbearing age make up a large percentage of its migrant factory worker population. Understanding their immunity to rubella is critical in furthering efforts towards rubella vaccination programs.

Objectives

To investigate the seronegativity of rubella antibodies and evaluate potential associates of rubella immunity among female migrant factory workers in Shenzhen, China.

Subjects and Methods

: Serum samples were collected from 518 female migrant workers, aged 18–55, working in 44 randomly selected factories in Shenzhen, China during May through June of 2009. Samples were tested for Rubella Immunoglobulin G (IgG) using a commercial Enzyme-linked immunosorbant assay kit. Self-reported vaccination histories and socio-demographic information were also collected.

Results

Of 518 female workers, 402 (77.6%) were immune to rubella. Significant differences in seronegativity were dependent on region of origin, being without a job contract, age group, marital status and seronegativity of measles.

Conclusions

Seroprevalence of antibodies to rubella in Shenzhen, China amongst female migrant workers is too low to provide immunity in the population. Given the high numbers of women of childbearing age amongst Shenzhen migrant factory workers coming from many provinces across China, local health authorities in Shenzhen should consider combining new rubella immunization programs with existing measles immunization efforts in this population.     

Seroprevalence of rubella antibodies in The Netherlands after 32 years of high vaccination coverage

Here we present rubella virus specific antibody levels in a large cross-sectional population-based serosurveillance study performed in The Netherlands in 2006/2007.     

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-prevalence of rubella among pregnant women in India, 2017

BackgroundWe conducted a sero-survey among pregnant women attending antenatal clinics of six hospitals which also function as sentinel sites for CRS surveillance, to estimate the prevalence of IgG antibodies against rubella.MethodsWe systematically sampled 1800 pregnant women attending antenatal clinics and tested their sera for IgG antibodies against rubella. We classified sera as seropositive (titre ≥10 IU/ml), sero-negative (titre <8 IU/ml) or indeterminate (titre 8–9.9 IU/ml) per manufacturer's instructions. In a sub-sample, we estimated the titers of IgG antibodies against rubella. IgG titer of ≥10 IU/mL was considered protective.ResultsOf 1800 sera tested, 1502 (83.4%) were seropositive and 24 (1.3%) were indeterminate and 274 (15.2%) were sero-negative. Rubella sero-positivity did not differ by age group, educational status or place of residence. Three hundred and eighty three (87.8%) of the 436 sera had IgG concentrations ≥10 IU/mL.ConclusionThe results of the serosurvey indicate high levels of rubella sero-positivity in pregnant women. High sero-prevalence in the absence of routine childhood immunization indicates continued transmission of rubella virus in cities where sentinel sites are located.     

A review of testing used in seroprevalence studies on measles and rubella

Seroprevalence studies are an essential tool to monitor the efficacy of vaccination programmes, to understand population immunity and to identify populations at higher risk of infection. An overarching review of all aspects of seroprevalence studies for measles and rubella published between 1998 and June 2014 was undertaken and the findings reported elsewhere. This paper details the considerable variation in the testing formats identified in the review. Apart from serum/plasma samples, testing of oral fluid, breast milk, dry blood spots and capillary whole blood were reported. Numerous different commercial assays were employed, including microtitre plate assays, automated immunoassays and classical haemagglutination inhibition and neutralisation assays. A total of 29 of the 68 (43%) measles and 14 of the 58 (24%) rubella studies reported qualitative test results. Very little information on the testing environment, including quality assurance mechanisms used, was provided. Due to the large numbers of testing systems, the diversity of sample types used and the difficulties in accurate quantification of antibody levels, the results reported in individual studies were not necessarily comparable. Further efforts to standardise seroprevalence studies may overcome this deficiency.     

Measles and rubella immunity in the population of Bhutan, 2017

BackgroundIn 2017, measles elimination was verified in Bhutan, and the country appears to have sufficiently high vaccination coverage to achieve rubella elimination. However, a measles and rubella serosurvey was conducted to find if any hidden immunity gaps existed that could threaten Bhutan’s elimination status.MethodsA nationwide, three-stage, cluster seroprevalence survey was conducted among individuals aged 1–4, 5–17, and >20 years in 2017. Demographic information and children’s vaccination history were collected, and a blood specimen was drawn. Serum was tested for measles and rubella immunoglobulin G (IgG). Frequencies, weighted proportions, and prevalence ratios for measles and rubella seropositivity were calculated by demographic and vaccination history, taking into account the study design.ResultsOf the 1325 individuals tested, 1045 (81%, 95% CI 78%–85%) were measles IgG seropositive, and 1290 (97%, 95% CI 95%–99%) were rubella IgG seropositive. Rubella IgG seropositivity was high in all three age strata, but only 47% of those aged 5–17 years were measles IgG seropositive. Additionally, only 41% of those aged 5–17 years who had documented receipt of two doses of measles– or measles-rubella–containing vaccine were seropositive for measles IgG, but almost all these children were rubella IgG seropositive.ConclusionsAn unexpected measles immunity gap was identified among children 5–17 years of age. It is unclear why this immunity gap exists; however, it could have led to a large outbreak and threatened sustaining of measles elimination in Bhutan. Based on this finding, a mass vaccination campaign was conducted to close the immunity gap.     

Seroprevalence of varicella antibodies among pregnant women in Lyon-France

The purpose of the study was to calculate the seroprevalence of immunity to the varicella-zoster virus (VZV) infection and to evaluate the positive predictive value (PPV) and the negative predictive value (NPV) of the self-reported history of VZV infection in pregnant women. A cross sectional study was conducted in 18 private medical analysis laboratories. Information on socio-demographic characteristics and past history of varicella or zoster were collected using a questionnaire. Blood samples were obtained to determine the serological levels of past exposure to VZV. Overall, 486 pregnant women were recruited. The seroprevalence of VZV antibodies was 98.8%. Six women were seronegative, of whom four were primiparous. The PPV was high (99.5%) while the NPV was only 10.3%. The PPV is a reliable marker of prior VZV infection. In contrast, a negative history does not predict lack of immunity and should be completed by serological analysis which might be introduced to routine antenatal blood tests.     

A 16-year review of seroprevalence studies on measles and rubella

The determination of the seroprevalence of vaccine-preventable diseases is critical in monitoring the efficacy of vaccination programmes and to assess the gaps in population immunity but requires extensive organisation and is time and resource intensive. The results of the studies are frequently reported in peer-reviewed scientific, government and non-government publications. A review of scientific literature was undertaken to advise the development of WHO guidelines for the assessment of measles and rubella seroprevalence. A search of the National Library of Medicine’s PubMed online publications using key words of ‘measles’, ‘rubella’, combined with ‘serosurvey’, ‘seroprevalence’, ‘immunity’ and ‘population immunity’ was conducted. A total of 97 articles published between January 1998 and June 2014 were retrieved, 68 describing serosurveys for measles and 58 serosurveys for rubella, conducted in 37 and 36 different countries respectively. Only 13 (19%) and 8 (14%) respectively were UN classified “least developed countries”. The study sample varied markedly and included combinations of male and female infants, children, adolescents and adults. The study sizes also varied with 28% and 33% of measles and rubella studies respectively, having greater than 2000 participants. Microtitre plate enzyme immunoassays were used in 52 (76%) measles studies and 40 (69%) rubella studies. A total of 39 (57%) measles and 44 (76%) rubella studies reported quantitative test results. Seroprevalence ranged from 60.8% to 95.9% for measles and 53.0% to 99.3% for rubella studies. The review highlighted that infants lost maternally-acquired immunity within 9 months of birth and were unprotected until vaccination. Two groups at higher risk of infection were identified: young adults between the ages of 15 and 30 years and immigrants.     

High rate of rubella seronegativity in perinatally-infected HIV women of childbearing age: A case-control study

Rubella infection is a vaccine preventable disease. Maternal infection during pregnancy may lead to congenital infection and severe foetal malformations. Thanks to antiretroviral therapy, perinatally HIV-infected women have better prognosis and are now experiencing pregnancy. We evaluated the rate of rubella seronegativity in a cohort of HIV perinatally-infected women of childbearing age. A high rate of seronegativity was found in this group as compared to age-matched non-perinatally infected HIV-infected women (34.5% vs 6.90%, p < 0.01). MMR administration before rubella testing was identified in 75.8% of perinatally-infected women (22/29) with a mean of 2 doses (range: 1–3 doses). HIV perinatally-infected women of childbearing age should be screened repeatedly for rubella immunity.     

Comparing the rubella seronegativity in pregnant women who received one dose of rubella vaccine at different ages in Taiwan

IntroductionVaccination is the best strategy to prevent rubella and congenital rubella. The aim of our study was to assess the immunity to rubella and determine rubella virus antibody titers in pregnant women who were offered a single dose of rubella vaccine at different ages of their lives.MethodsA total 15,067 rubella IgG antibody test results for Taiwanese pregnant women who received routine prenatal checkup at Fooyin University Hospital from 1999 to 2014 were analyzed in this study. The women were divided into five birth cohorts in order to compare their rubella seronegativities and antibody titers according to the different period of rubella vaccination policy in Taiwan.ResultsThe total rubella seronegativity rate was 11.2% (95% CI: 10.7–11.7%) and the mean rubella antibody titers was 51.0 IU/mL (SD = 54.7 IU/mL). The junior school cohort has the lowest rubella seronegativity of 7.6% (95% CI: 6.9–8.2%). The seronegativities were significantly high in the preschool cohort and in the 15-month-old cohort, 14.9% (95% CI: 13.2–16.6%) and 14.8% (95% CI: 11.5–18.1%), respectively. The OR values were 2.1 (95% CI: 1.8–2.5, p < 0.001) in the preschool cohort and 2.2 (95% CI: 1.6–2.8, p < 0.001) in the 15-month-old cohort, respectively, against the junior school cohort. Women in the 15-month-old cohort have lowest average rubella IgG titer, 25.4 IU/mL.ConclusionThe total rubella seronegativity rate was 11.2% in all native pregnant women. Women who received one dose rubella vaccine at preschool and 15-month-old have highest seronegativities. The 15-month-old cohort has the lowest average rubella IgG titer. We recommend a revised catch-up immunization policy to women who received one dose rubella vaccine at a younger age.     

Measles and rubella IgG seroprevalence in persons 6 month-35 years of age,Mongolia, 2016

BackgroundIn 2015–2016, Mongolia experienced an unexpected large measles outbreak affecting mostly young children and adults. After two nationwide vaccination campaigns, measles transmission declined. To determine if there were any remaining immunity gaps to measles or rubella in the population, a nationally representative serosurvey for measles and rubella antibodies was conducted after the outbreak was over.MethodsA nationwide, cross-sectional, stratified, three-stage cluster serosurvey was conducted in November-December 2016. A priori, four regional strata (Ulaanbaatar, Western, Central, and Gobi-Eastern) and five age strata (6 months-23 months, 2–7 years, 8–17 years, 18–30 years, and 31–35 years) were created. Households were visited, members interviewed, and blood specimens were collected from age-appropriate members. Blood specimens were tested for measles immunoglobulin G (IgG) and rubella IgG (Enzygnost® Anti-measles Virus/IgG and Anti-rubella Virus/IgG, Siemens, Healthcare Diagnostics Products, GmbH Marburg, Germany). Factors associated with seropositivity were evaluated.ResultsAmong 4598 persons aged 6 months to 35 years participating in the serosurvey, 94% were measles IgG positive and 95% were rubella IgG positive. Measles IgG seropositivity was associated with increasing age and higher education. Rubella IgG seropositivity was associated with increasing age, higher education, smaller household size, receipt of MMR in routine immunization, residence outside the Western Region, non-Muslim religious affiliation, and non-Kazakh ethnicity. Muslim Kazakhs living in Western Region had the lowest rubella seroprevalence of all survey participants.ConclusionsNationally, high immunity to both measles and rubella has been achieved among persons 1–35 years of age, which should be sufficient to eliminate both measles and rubella if future birth cohorts have ≥ 95% two dose vaccination coverage. Catch-up vaccination is needed to close immunity gaps found among some subpopulations, particularly Muslim Kazakhs living in Western Region.     

Seroprevalence of antibodies against rubella virus in pregnant women in Haiti.

OBJECTIVE: To assess the seroprevalence of immunity to the rubella virus in pregnant women in Haiti attending the Obstetrics and Gynecology Department of the State University Hospital, in the capital city of Port-au-Prince, in order to help with the introduction of the rubella vaccine for the population and provide protection for women of reproductive age in the country. METHODS: This cross-sectional study was done between February 2002 and May 2002. A total of 503 pregnant women were tested for rubella-specific immunoglobulin G antibodies, using enzyme immunoassay; 8 of those women were later excluded because they did not know their age, leaving 495 women in the analysis. RESULTS: Of the 495 participants included in our analysis, 471 of them (95.2%) were seropositive; only 24 of them (4.8%) were seronegative (susceptible). A statistically significant difference (P = 0.02) was found in the rate of seronegativity for rubella virus between the pregnant women living in the Port-au-Prince area (17 of 426 women, or 4.0%) and those living in rural areas (7 of 69 women, or 10.1%). In terms of age, 81 of the 495 (16.4%) women were under 21 years ld. CONCLUSIONS: This study is an important first step in addressing the issue of prevalence of rubella virus infection among Haitian women and in dealing with the still-underrecognized public health problem of congenital rubella syndrome in Haiti. We recommend additional research that uses randomized sampling and includes a significant proportion of women from rural areas of the country.     

Seroprevalence and durability of rubella virus antibodies in a highly immunized population

BackgroundAlthough the administration of the measles-mumps-rubella (MMR) vaccine has been widespread in the United States for decades, gaps in vaccine coverage still persist for various reasons. The maintenance of herd immunity against rubella virus (RV) is important to controlling the spread and resurgence of rubella and congenital rubella syndrome.MethodsIn this study, we sought to assess the seroprevalence of RV-specific antibodies in an adult population from a defined geographic area in Olmsted County, MN, and the surrounding municipalities, with relatively high vaccine coverage and no documented evidence of circulating RV in the past 24 years. Rubella-specific IgG antibodies were measured by ELISA in a large set of serum samples (n = 1393) obtained from the Mayo Clinic Biobank. This cohort was 80.2% female and ranged from 20 to 44 years of age.ResultsIn total, 97.8% of subjects were seropositive for rubella-specific IgG antibodies, with a median titer of 40.56 IU/mL, suggesting a high degree of immunization; however, 2.2% of subjects were found to be seronegative. Interestingly, 25.1% of subjects were seropositive but had titers lower than 25 IU/mL, indicating either a population of low responders or individuals that could potentially be at risk of waning immunity. No significant associations or differences were found between RV-specific titers and demographic variables such as age, sex, or body mass index (BMI).ConclusionsA high rate of seropositivity for rubella was found among this young adult cohort, but a significant percent of the cohort had lower titers that may indicate poor initial vaccine response and potential risk if their antibody titers decline.     

北京市朝阳区孕妇麻疹和风疹抗体水平调查

目的 了解孕妇麻疹、风疹抗体水平,为控制小月龄儿童麻疹发病和先天性风疹综合征(CRS)提供科学依据.方法 采集北京市朝阳区孕妇产前静脉血,使用ELLSA方法进行麻疹IgG和风疹IgG抗体水平检测.结果朝阳区孕妇麻疹IgG抗体几何平均浓度和阳性率分别为550.27mlU/ml和81.4%,风疹IgG抗体几何平均浓度和阳性...     

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

BackgroundVaccinating 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.MethodsPregnant 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.ResultsA 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.ConclusionsThe 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.