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.