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

Factors Predicting Rubella Vaccination among Pregnant Women in Japan: an Interim Report from the Pregnant Women Health Initiative

Following the 2018 rubella outbreak in Japan, this study aimed to assess rubella prevention measures based on the vaccination and immunization status of pregnant women in Japan. Our cohort study involved 3 local core hospitals in Yokohama City, and a total of 666 pregnant women were recruited between June 2018 and September 2019 and answered an online questionnaire. In total, 67.5% of the pregnant women had received rubella vaccination. The rate of rubella vaccination among pregnant women in the present survey was lower than that among age-matched female participants in a nationwide survey conducted in 2018. Overall, the study results showed that pregnant women in their 20s had a higher vaccination rate than those in their 40s, women who were nonsmokers before pregnancy had a higher vaccination rate than those who were smokers, and pregnant women who were aware that rubella may affect their fetuses had a higher vaccination rate than those who were unaware of this. This survey elucidated multiple predictive factors for rubella vaccination among pregnant women in Japan. Our results confirm the recommendation that women considering pregnancy should be vaccinated against rubella.

Faster waning of the rubella-specific immune response in young pregnant women immunized with MMR at 15 months

PROBLEM

Vaccination is the best protection against rubella and congenital rubella infection. Although a high rate of immunization coverage is achieved in Taiwan, it is unknown if the vaccine-induced immunity persists from the age of vaccination to childbearing age.

METHODS OF STUDY

A total of 5,988 prenatal rubella IgG test results of young pregnant women aged 19-23 years old from six hospitals during January 2001 to December 2008 and January 2013 to December 2017 were analyzed. We compared the rubella seropositivity rates and titers in these women who were vaccinated with MMR vaccine in four different vaccination age cohorts.

RESULTS

The overall rubella seropositivity rate was 87.4% (95% CI: 86.6%-88.3%), and the mean rubella IgG level was 39 IU/mL among young pregnant women aged 19-23 years. Women in the elementary cohort had the highest rubella positivity of 90.8% (95% CI: 89.6%-91.9%), and levels gradually decrease to 84.6% (95% CI: 82.4%-86.7%) in 15-month plus cohort. The average rubella IgG was only 25 IU/mL for the 15-month plus cohort. Women in cohorts immunized at younger age exhibited significantly lower chances of being seropositive relative to women in older cohort after adjusting other factors (all P < .01).

CONCLUSION

The rubella seropositivity rate and rubella IgG levels were low among young women aged 19-23 years, especially in cohorts immunized at younger age. As rubella immunity wanes over time, a third dose of MMR may be a protective strategy for women who conceive later in life.

Phylogeography of rubella virus in Asia: Vaccination and demography shape synchronous outbreaks

Rubella virus causes mild disease in children but for women in the early stages of pregnancy, it can cause spontaneous abortion, congenital rubella syndrome (CRS) and associated birth defects. Despite the availability of an effective vaccine, rubella virus continues to circulate endemically in several regions of the world. This is particularly true in East and Southeast (E/SE) Asia, where control efforts vary widely among countries that are well connected through travel and immigration. It is therefore important to understand how the regional persistence of rubella is affected both by dynamics occurring across countries and susceptibility within countries. Here, we use genetic and epidemiological data from countries in E/SE Asia to explore the phylogeography of rubella virus in this region. Our results underline that metapopulation dynamics are key for rubella persistence and highlight the source-sink population structure of the region. We identify countries that contribute to the regional metapopulation network and link epidemic dynamics to susceptibility profiles within each country. Our results indicate that human movement plays an important role in driving epidemic dynamics in E/SE Asia.

Comparison of two commercial ELISA kits for detection of rubella specific IgM in suspected congenital rubella syndrome cases and rubella IgG antibodies in a serosurvey of pregnant women

Enzyme linked immunosorbent assay (ELISA) for antibody identification, is important for laboratory confirmation of rubella infection in different settings. The Enzygnost rubella ELISA, widely used in the World Health Organization (WHO) Global Measles and Rubella Laboratory Network, is expensive and often unavailable. Qualitative and quantitative performance of the Euroimmun ELISA was compared with the Enzygnost ELISA, for detection of rubella specific IgM, using 283 sera collected from suspected congenital rubella syndrome (CRS) patients and IgG antibodies using 435 sera from a serosurvey among pregnant women. Good qualitative agreement was observed for detection of both rubella specific IgM (94.7% agreement and κ of 0.86) and IgG (96.3% agreement and κ of 0.84). Bland-Altman analysis for IgG yielded a mean difference of 0.781 IU/ml with 97.1% values within ±2 SD of the mean difference. Our study findings suggest that Euroimmun ELISA may be considered for detection of rubella specific IgM in suspected CRS cases and rubella specific IgG in surveillance studies.