title: The economic impact of prenatal varicella immunity among pregnant women in Alberta.
abstract: In light of the changing epidemiology of varicella, we sought to examine varicella antibody levels in the prenatal population in the Canadian province of Alberta. All prenatal varicella screening tests performed between August 1, 2002 and February 2, 2014 (454,592) were included in this study. Test results, demographics and vaccination status were examined to identify varicella seroprevalence and correlates for being seronegative. An overall seroprevalence for varicella of 95.8% was found across all pregnancy screenings. Significant independent correlates of seronegativity included younger age (AOR: 4.72 (95% CI: 3.87-5.77) for <20years of age vs. >40years of age) and having immigrated to Alberta from Africa or Asia (AOR: 4.55 (95% CI: 4.10-5.05) and AOR: 5.83 (95%CI; 5.48-6.19), respectively). Women who were initially seronegative for varicella antibodies and who received both postnatal vaccination and post-vaccination prenatal screening (2566) were examined to assess seroconversion. 66.3% of women who were tested up to six months post-vaccination were seropositive, however only 36.9% of women tested after 36months were seropositive. Finally, 40.9% of all prenatal varicella specimens tested were deemed redundant, i.e. women had either a history of (1) ⩾2 doses of varicella vaccine, (2) varicella infection, or (3) a previous positive varicella serology. Eliminating this redundant screening could provide an estimated $96,000 in savings annually in laboratory and Public Health follow-up costs alone. As the number of women with vaccine-derived immunity through universal childhood vaccination increase in the prenatal population, screening methods may need to adapt to ensure varicella immunity is accurately conducted and assessed.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Amrit
authors.initials: A
authors.lastname: Passi
authors.affiliation: Public Health Agency of Canada, Ottawa, ON, Canada; School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Sabrina S
authors.initials: SS
authors.lastname: Plitt
authors.affiliation: Alberta Health, Edmonton, Alberta, Canada; Department of Cardiovascular Sciences, University of Leicester, United Kingdom(1).
authors.forename: Florence Y
authors.initials: FY
authors.lastname: Lai
authors.affiliation: School of Public Health, University of Alberta, Edmonton, Alberta, Canada; Alberta Health, Edmonton, Alberta, Canada; Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Kimberley
authors.initials: K
authors.lastname: Simmonds
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Provincial Laboratory for Public Health (ProvLab), Alberta, Canada. Electronic address: Carmen.Charlton@albertahealthservices.ca.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Charlton
mesh_terms: D000328:Adult; D000416:Alberta / Q000453:epidemiology; D002644:Chickenpox / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000191:economics* / Q000706:statistics & numerical data*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology / Q000517:prevention & control*; D037841:Pregnant People; D016036:Seroepidemiologic Studies; D012698:Serologic Tests / Q000191:economics* / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: Pregnancy; Seroprevalence; Vaccination; Varicella