Transmission dynamics of the rubella virus circulating in China during 2010-2019: two lineage switches between genotypes 1E and 2B

Do adolescents need a rubella vaccination campaign? Rubella serosurvey among healthy children in Hangzhou, China

The aim of this study was to evaluate the seroprevalence of rubella antibodies and factors associated with antibody seropositivity after vaccination among healthy children aged 14 and below. A multi-stage stratified random sampling method was employed to recruit participants for the rubella serological test. An enzyme-linked immunosorbent assay method was used to detect human IgG antibodies with avidity for rubella virus in the sera of participants. Univariate and multivariate analyses were used to analyze associations between variables. A total of 778 subjects were included in the subsequent analysis. The overall positive rate of rubella antibody was 83.0% (95%CI: 80.2-85.5%), and the overall geometric mean concentration (GMC) was 58.05 IU/ml. In multivariate analysis, gender, residence, birth year group, and time since the last rubella-containing vaccines (RCV) vaccination were significantly associated with the seroprevalence of rubella antibodies. Our study showed a decreasing trend in rubella antibody positivity and GMC in the population aged five to 14 years. Therefore, we recommend a catch-up dose of RCV for adolescents and young people aged over 14 years not yet vaccinated.

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 supplementaryimmunizationactivities, 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.

Importation and circulation of rubella virus lineages 1E-L2 and 2B-L2c between 2018 and 2021 in China: Virus evolution and spatial-temporal transmission characteristics

To better understand the importation and circulation patterns of rubella virus lineages 1E-L2 and 2B-L2c circulating in China since 2018, 3,312 viral strains collected from 27 out of 31 provinces in China between 2018 and 2021 were sequenced and analyzed with the representative international strains of lineages 1E-L2 and 2B-L2c based on genotyping region. Time-scale phylogenetic analysis revealed that the global lineages 1E-L2 and 2B-L2c presented distinct evolutionary patterns. Lineage 1E-L2 circulated in relatively limited geographical areas (mainly Asia) and showed geographical and temporal clustering, while lineage 2B-L2c strains circulated widely throughout the world and exhibited a complicated topology with several independently evolved branches. Furthermore, both lineages showed extensive international transmission activities, and phylogeographic inference provided evidence that lineage 1E-L2 strains circulating in China possibly originated from Japan, while the source of lineage 2B-L2c isolated since 2018 is still unclear. After importation into China in 2018, the spread of lineage 1E-L2 presented a three-stage transmission pattern from southern to northern China, whereas lineage 2B-L2c spread from a single point in western China to all the other four regions. These two transmission patterns allowed both imported lineages to spread rapidly across China during the 2018-9 rubella epidemic and eventually established endemic circulations. This study provides critical scientific data for rubella control and elimination in China and worldwide.