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.     

Immunogenicity,duration of protection,effectiveness and safety of rubella containing vaccines: A systematic literature review and meta-analysis

BackgroundRubella containing vaccines (RCV) prevent rubella virus infection and subsequent congenital rubella syndrome (CRS). To update the evidence on immunogenicity, duration of protection, effectiveness and safety of RCV, we conducted a systematic literature review.MethodsWe searched EMBASE and SCOPUS, using keywords for rubella vaccine in combination with immunogenicity (seroconversion and seropositivity), duration of protection, efficacy/effectiveness, and safety. Original research papers involving at least one dose of RCV (at any age), published between 1-1-2010 and 17-5-2019 were included. Where appropriate, meta-analyses were performed. Quality of included studies was assessed using GRADE methodology.ResultsWe included 36 papers (32 randomized controlled trials (RCTs) and 4 observational studies) on immunogenicity (RA27/3 strain) in children and adolescent girls, 14 papers (5 RCTs and 9 observational studies) on duration of protection, one paper on vaccine effectiveness (VE) (BRDII strain), and 74 studies on safety, including three on safety in pregnancy.Meta-analysis of immunogenicity data showed 99% seroconversion (95% CI: 98–99%) after a single dose of RCV in children, independent of co-administration with other vaccines. Seroconversion after RCV1 below 9 months of age (BRDII strain, at 8 months) was 93% (95% CI: 92–95%). For duration of protection, the included studies showed a seropositivity of 88%-100% measured 1–20 years after one or two RCV doses. The single study on VE of BRDII strain, reported 100% VE after one and two doses. Among 34,332 individuals participating in the RCTs, 140 severe adverse events (SAEs) were reported as possibly related to RCV. Among the case reports on SAEs, the association with RCV was confirmed in one report (on fulminant encephalitis). Among 3,000 pregnant women who were inadvertently vaccinated, no SAEs were reported.ConclusionsOne and two doses of RCV are highly immunogenic for a long period of time, effective in preventing rubella and CRS, and safe.     

Epidemiological profile and progress toward rubella elimination in China. 10 years after nationwide introduction of rubella vaccine

BackgroundRubella-containing vaccine (RCV) became available in China in 1993 and was introduced nationwide into the Expanded Immunization Program (EPI) in 2008. We evaluated implementation and impact of RCV from 2 years prior to nationwide introduction through the 10 years after nationwide introduction.MethodsWe analyzed RCV lot-release (doses distributed) data, 1- and 2-dose RCV coverage, and rubella data from China’s nationwide disease surveillance system to describe the current status and changes in rubella epidemiology between 2005 and 2017.ResultsWhile the vaccine was included into the routine immunization program in 2008, its full implementation required 4 years due to sporadic vaccine supply constraints. RCV1 and RCV2 coverage increased from 51.5% and 39.0% in 2008 to >95% during 2012 through 2016. From 2005 to 2017, the annual incidences (per million) of rubella ranged from 91.09 in 2008 down to 1.16 in 2017; reductions occurred in all age groups. The proportion of cases among individuals ≥20 years old increased from 0.97% in 2005 to 31.2% in 2017. In the better-developed eastern China, most cases were among adults; in central and western China, most cases were among children or adolescents.ConclusionsThe marked decrease rubella was a result of inclusion of RCVs into EPI targeting children less than 2 years of age and achieving high level of 2-dose coverage. Rubella was reduced in absolute terms, and its epidemiology was changed to older cases with substantial inter-province variation. Ensuring full vaccination of school children and identifying strategies to reach adults with measles and rubella combined vaccines will be important to hasten elimination of rubella and prevent CRS outbreaks.     

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.     

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.     

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

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

Molecular surveillance of rubella virus in Beijing,China during 2010–2021: Progress and challenges in rubella elimination

Rubella is listed by the World Health Organization (WHO) as a disease that needs to be eliminated worldwide. The aim of this study was to understand the progress and challenges towards rubella elimination in Beijing, China, by analyzing molecular surveillance data combined with immunization and surveillance strategies as well as epidemiological data. With high immunization coverage under the 3-dose policy (8 months, 18 months, and 6 years) and supplementary immunization activities for the floating population, rubella incidence showed a downward trend since 2010, despite two epidemics that occurred in 2014–2015 and 2019. The reported rubella cases were generally concentrated in the age group of 15–34 years. Although citywide surveillance for congenital rubella syndrome (CRS) has been carried out since 2016, only one case has been confirmed by laboratory testing. Furthermore, molecular surveillance data showed that rubella viruses (RVs) circulating in Beijing during 2010–2020 were evidently heterogeneous; the domestic lineage 1E-L1 and multiple imported lineages, including 2B-L1, 1E-L2, and 2B-L2c, were identified in the last decade. Meanwhile, two lineage-related switches were determined, including the displacement of lineage 1E-L1 with lineage 2B-L1 around 2014 and the transition between lineage 2B-L1 and lineage 1E-L2 and 2B-L2c in 2018–2019. This RV transmission pattern was similar to that observed across the country, whereas lineages 1E-L1 and 2B-L2c were prevalent in Beijing for a shorter period. Overall, these results indicate the need to maintain routine immunization with rubella-containing vaccines, promote regular supplementary immunization activities, and enhance rubella and CRS surveillance even in order to accelerate rubella elimination in Beijing. Further, the existing immunization strategies must be optimized to further close the immunity gap.     

Determining rubella immunity in pregnant Alberta women 2009–2012

Rubella IgG levels for 157,763 pregnant women residing in Alberta between 2009 and 2012 were analyzed. As there have been no reported cases of indigenous rubella infection in Canada since 2005, there has been a lack of naturally acquired immunity, and the current prenatal population depends almost entirely on vaccine induced immunity for protection. Rubella antibody levels are significantly lower in younger maternal cohorts with 16.8% of those born prior to universal vaccination programs (1971–1980), and 33.8% of those born after (1981–1990) having IgG levels that are not considered protective (<15 IU/mL). Analysis across pregnancies showed only 35.0% of women responded with a 4-fold increase in antibody levels following post-natal vaccination. Additionally, 41.2% of women with antibody levels <15 IU/mL had previously received 2 doses of rubella containing vaccine. These discordant interpretations generate a great deal of confusion for laboratorians and physicians alike, and result in significant patient follow-up by Public Health teams. To assess the current antibody levels in the prenatal population, latent class modeling was employed to generate a two class fit model representing women with an antibody response to rubella, and women without an antibody response. The declining level of vaccine-induced antibodies in our population is disconcerting, and a combined approach from the laboratory and Public Health may be required to provide appropriate follow up for women who are truly susceptible to rubella infection.     

Effectiveness of Rubella vaccine in a rubella outbreak in Guangzhou city,China, 2014

BackgroundWHO recommends the use of rubella-containing vaccine (RCVs) to prevent rubella and congenital rubella syndrome (CRS). Most licensed rubella vaccines in use globally are based on RA27/3 strains and have estimated vaccine effectiveness (VE) rates of 95–100%. In contrast, China uses a BRD-II strain-based rubella vaccine. Few field studies have been conducted that estimate VE of China's RCV. On March 17, 2014, a rubella outbreak was reported in a middle school in Guangzhou city, China. We conducted an investigation to understand reasons for the outbreak, and we used that investigation to estimate vaccine effectiveness of China's rubella vaccine.MethodsTo identify cases, investigators reviewed records kept by the school doctor and absentee records kept by teachers. Self-administered questionnaires were sent to parents of all students to collect information about the students’ symptoms, the results of any physician consultation, and disease history. We obtained demographic information and illness information for all students in the school; vaccination status was determined by inspection of official, parent-held vaccination records. A retrospective cohort study was conducted in 13 classes that had secondary cases of rubella. Using the secondary attack rates, we evaluated VE by the number of RCV doses received and age at vaccination.ResultsDuring the period February 17–May 23, 2014, 162 students (50 suspected cases, 88 probable cases, 24 confirmed cases) were diagnosed with rubella, yielding an overall attack rate of 10% (162/1621). Cases occurred in 27 classes (73%) of 37 classrooms. Secondary cases occurred in 13 classes (35%) of 37 classrooms. A total of 1130 students (69.7%) have vaccination certificates; 419 (37%) students were record-confirmed to have received RCV. For those vaccinated using BRD-II strain vaccine, vaccine effectiveness (VE) was 94% (95%CI: 75–98). VE for measles, mumps, and rubella (MMR) vaccine which is based on either BRD-II or RA27/3 strain was 89% (95%CI: 56–97). VE of a single dose of domestic monovalent rubella vaccine that used BRD-II strain vaccine was 93% (95%CI: 73–98). VE for those who received the vaccine between 1 and 2 years of age was 95% (95% CI: 67–99) while the VE was 100% for those vaccinated after 2 years of age. VE among those who received RCV <12 years ago was 100% while VE among those who received RCV ≥12 years ago was 92% (95%CI: 70–98).ConclusionsThe rubella vaccines used in China that are based on the BRD-II rubella vaccine strain have VE of 94%, which is similar to the more commonly used RA27/3-based RCVs. Low vaccination coverage contributed to this outbreak; early reporting of an outbreak is necessary for effective outbreak response immunization.     

Seroprevalence of rubella antibodies and determinants of susceptibility to rubella in a cohort of pregnant women in Canada, 2008–2011

Long term control of rubella and congenital rubella syndrome relies on high population-level immunity against rubella, particularly among women of childbearing age. In Canada, all pregnant women should be screened so that susceptible new mothers can be offered vaccination for rubella before discharge. This study was undertaken to estimate rubella susceptibility in a cohort of pregnant women in Canada and to identify associated socio-economic and demographic factors. Biobanked plasma samples were obtained from the Maternal-Infant Research on Environmental Chemicals (MIREC) study, in which pregnant women were recruited between 2008 and 2011. Socio-demographic characteristics and obstetric histories were collected. Second trimester plasma samples (n = 1,752) were tested for rubella-specific IgG using an in-house enzyme-linked immunosorbent assay. The percentage of women with IgG titers <5 IU/mL, 5–10 IU/mL, and ≥10 IU/mL were 2.3%, 10.1%, and 87.6%, respectively. Rates of seronegativity, defined as <5 IU/mL, were 3.1% in women who had no previous live birth and 1.6% in women who had given birth previously. Among the latter group, seronegativity was higher in women with high school education or less (adjusted OR (aOR) 5.93, 95% CI 2.08–16.96) or with a college or trade school diploma (aOR 3.82, 95% CI 1.45–10.12), compared to university graduates, and those born outside Canada (aOR 2.60, 95% CI 1.07–6.31). In conclusion, a large majority of pregnant women were found to be immune to rubella. Further research is needed to understand inequalities in vaccine uptake or access, and more effort is needed to promote catch-up measles-mumps-rubella vaccination among socioeconomically disadvantaged and immigrant women of childbearing age.     

Rubella virus immunization status in preconception period among Chinese women of reproductive age: A nation-wide,cross-sectional study

ObjectivePopulation-based studies on sero-epidemiology of Rubella in women before conception are lacking. The aim of this study was to investigate the sero-prevalence of Rubella in a nationwide survey among Chinese women planning to get pregnant within six months.MethodsThis population-based, cross-sectional, sero-survey of Rubella virus infection was a part of the National Free Preconception Health Examination Project covering all 31 provinces in Mainland China. Women intending to get pregnant within six months was enrolled between 2010 and 12. Information on demographic characteristics (age, residence status, race, education and occupation) and vaccination history was obtained by interviews. Rubella virus IgG sero-positivity was determined using venous blood samples.ResultsOf 2,120,131 women recruited to the study, Rubella virus IgG serology was available in 1,974,188 (99.3%). Participating women were of young age (median = 28 years), mostly engaged in agricultural activities (78%), and the majority (90%) had high school education or lower. The overall prevalence of Rubella virus IgG sero-positivity was 58.4% (1,161,129); geographical variation ranged from 92.5% in Jilin to 20.1% in Qinghai and 0.0% in Tibet. Only 4.6% (n = 91,604) women reported to have had Rubella virus vaccination, and it varied from 18.6% (Guangdong) to 0.2% (Qinghai). Self-reported vaccination status did not correlate with Rubella virus IgG seropositivity.ConclusionsPrevalence of Rubella sero-positivity is low among Chinese women of reproductive age and there are significant regional differences. Over 40% of women being susceptible to Rubella in preconception period calls for a targeted screening and vaccination strategy.     

Surveillance of congenital rubella syndrome (CRS) in tertiary care hospitals in Hanoi,Vietnam during a rubella epidemic

ObjectiveTo describe the epidemiology and clinical features of congenital rubella syndrome (CRS) in Hanoi, Vietnam.MethodsProspective surveillance of CRS between May 2011 and March 2012 in Hanoi, Vietnam. CRS burden was assessed by clinical examination and collection of serum samples from infants in neonatology, cardiology and pediatric departments of two tertiary care hospitals in Hanoi. All infants born during the study period with clinical manifestations of CRS and seropositivity (IgM) for rubella were included in this study.ResultsDuring the surveillance period 113 infants were identified with confirmed CRS (clinical features and positive rubella IgM). Their mean age at diagnosis was 38.4 days (range 1–152 days) and 61% were female. Clinical manifestations of CRS included low birth weight <2500 g (86.0%), congenital heart disease (63.7%), hearing impairment (63.7%) and ophthalmological abnormalities (46.9%). Other clinical features at birth included: thrombocytopenia (85.0%), neonatal purpura (74.3%), splenomegaly (63.7%), hepatomegaly (62.8%) and blueberry muffin rash (61.1%). Among the mothers of infants with confirmed CRS none had received a rubella vaccine in the past and 88.4% gave a history of rubella contact during the pregnancy under study. In most cases (84.1%) maternal infection occurred in the first trimester. During the surveillance period the estimated annual incidence of CRS was 1.13/1000 live births (95% CI 0.92–1.34).ConclusionsThese preliminary baseline data show a high burden of CRS in Hanoi, Vietnam and the urgent need for universal vaccination. Surveillance to determine and monitor the national burden of CRS is essential.     

Immunogenicity and estimation of antibody persistence following vaccination with an inactivated virosomal hepatitis A vaccine in adults: A 20-year follow-up study

PurposeThis was a 20-year follow-up study to assess long-term persistence of protective antibody levels against the hepatitis A virus (HAV) in healthy participants vaccinated with 2 doses of inactivated hepatitis A vaccine (Epaxal®) between 1992 and 1995.MethodsBlood samples for anti-HAV antibody concentrations were obtained during a follow-up visit 20 years after vaccination and were analyzed in parallel with samples still available from previous visits using AxSYM® HAVAB 2.0 assay.ResultsMean (SD) age of the participants was 44.71 (3.905) years at year 20 follow-up (N = 95). Participants completing 0/12-month Epaxal® immunization regimen (N = 94) had seroprotection rate of 100% (95% CI: 96.2, 100.0) with ⩾10 mIU/mL seropositivity cut-off and 98.9% (95% CI: 94.2, 100.0) with ⩾20 mIU/mL cut-off. With ⩾10 mIU/mL cut-off, the estimated median duration of protection was 77.3 years (95% CI: 71.8, 83.5) with 95% of the vaccinated participants predicted to be protected for at least 41.5 years. At ⩾20 mIU/mL cut-off, the estimated median duration of protection was 64.8 years (95% CI: 60.1, 68.4) with 95% of the vaccinated participants predicted to be protected for at least 33 years. Anti-HAV antibody geometric mean concentrations were higher in women (277.9; 95% CI: 217.7, 354.7) than in men (167.7; 95% CI: 125.2, 224.6).ConclusionThe data from this 20-year follow-up study confirm previous observations that two doses of Epaxal® provide protection against hepatitis A infection for at least 30 years in over 95% of healthy participants.     

Seroprevalence of rubella among Jordanian women of childbearing age

This study was conducted to assess immunity (seroprevalence) to rubella among Jordanian women of childbearing age. A multistage cluster sampling was used to recruit 1125 women of childbearing age (15-49 year) from the 12 Governorates of Jordan. Anti-rubella antibody titers were measured using enzyme-linked immunoassays. The overall immunity rate to rubella among women in childbearing age was 90.9% (CI: 88.8-92.9). However, the immunity rate was significantly lower in younger women aged 15-19 years (83%) compared to the whole cohort (P相似文献   

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.     

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

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

Poliovirus seroprevalence before and after interruption of poliovirus transmission in Kano State,Nigeria

IntroductionIn September 2015, Nigeria was removed from the list of polio-endemic countries after more than 12 months had passed since the detection of last wild poliovirus case in the country on 24 July 2014. We are presenting here a report of two polio seroprevalence surveys conducted in September 2013 and October 2014, respectively, in the Kano state of northern Nigeria.MethodsHealth facility based seroprevalence surveys were undertaken at Murtala Mohammad Specialist Hospital, Kano. Parents or guardians of children aged 6–9 months, 36–47 months, 5–9 years and 10–14 years in 2013 and 6–9 months and 19–22 months (corresponding to 6–9 months range at the time of 2013 survey) in 2014 presenting to the outpatient department, were approached for participation, screened for eligibility and asked to provide informed consent. A questionnaire was administered and a blood sample collected for polio neutralization assay.ResultsAmong subjects aged 6–9 months in the 2013 survey, seroprevalence was 58% (95% confidence interval [CI] 51–66%) to poliovirus type 1, 42% (95% CI 34–50%) to poliovirus type 2, and 52% (95% CI 44–60%) to poliovirus type 3. Among children 36–47 months and older, seroprevalence was 85% or higher for all three serotypes. In 2014, seroprevalence in 6–9 month infants was 72% (95% CI 65–79%) for type 1, 59% (95% CI 52–66%) for type 2, and 65% (95% CI 57–72%) for type 3 and in 19–22 months, 80% (95% CI 74–85%), 57% (49–63%) and 78% (71–83%) respectively. Seroprevalence was positively associated with history of increasing oral poliovirus vaccine doses.ConclusionsThere was significant improvement in seroprevalence in 2014 over the 2013 levels indicating a positive impact of recent programmatic interventions. However the continued low seroprevalence in 6–9 month age is a concern and calls for improved immunization efforts to sustain the polio-free Nigeria.     

Durability of humoral immune responses to rubella following MMR vaccination

BackgroundWhile administration of the measles-mumps-rubella (MMR-II®) vaccine has been effective at preventing rubella infection in the United States, the durability of humoral immunity to the rubella component of MMR vaccine has not been widely studied among older adolescents and adults.MethodsIn this longitudinal study, we sought to assess the durability of rubella virus (RV)-specific humoral immunity in a healthy population (n = 98) of adolescents and young adults at two timepoints: ~7 and ~17 years after two doses of MMR-II® vaccination. Levels of circulating antibodies specific to RV were measured by ELISA and an immune-colorimetric neutralization assay. RV-specific memory B cell responses were also measured by ELISpot.ResultsRubella-specific IgG antibody titers, neutralizing antibody titers, and memory B cell responses declined with increasing time since vaccination; however, these decreases were relatively moderate. Memory B cell responses exhibited a greater decline in men compared to women.ConclusionsCollectively, rubella-specific humoral immunity declines following vaccination, although subjects’ antibody titers remain well above the currently recognized threshold for protective immunity. Clinical correlates of protection based on neutralizing antibody titer and memory B cell ELISpot response should be defined.     

Seroprevalence of rubella in school girls and pregnant women

Many studies have been assigned to investigate the surveillance of congenital rubella syndrome, acquired rubella and seroprevalence in different countries to determine the new vaccination program and national vaccination schedules. Seroprevalence of rubella in Turkey is still insufficient and national immunization schedules do not include routine rubella vaccination. In this study we aimed to investigate the seroprevalence of rubella at child bearing age in an unvaccinated population in Adana, southern Turkey, to help determine whether routine rubella vaccination is necessary, if so when it should be administered. Ninety-four school girls aged 12–18 years living in Adana were selected for the study and stratified according to the socioeconomic status of their parents and evaluated for rubella antibodies. One hundred pregnant women aged 18–25 years and 100 pregnant women aged 26–35 years were sampled rubella antibodies. Rubella specific IgG antibody was measured qualitatively and quantitatively by using microparticule enzyme immune assay technology. Rubella specific IgG antibody was positive in 87–94 school girls (92.5%). The geometric mean rubella specific IgG antibody value was found be 148.14 IU/ml. No correlation was found between socioeconomic status and rubella seropositivity (p = 0.6521). In all pregnant women rubella specific IgG antibody was found to be positive. In conclusion rubella vaccination should be considered carefully in developing countries. Because of the high seropositivity to rubella in our region we do not recommend rubella vaccination in early childhood. Yet this is a preliminary study and further studies with larger population size are needed to determine the national immunization policy for rubella.     

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

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