Seroprevalence of rubella antibodies and determinants of susceptibility to rubella in a cohort of pregnant women in Canada, 2008–2011
Article [Version publiée]
Résumé·s
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.