title: Immune status of health care workers to measles virus: evaluation of protective titers in four measles IgG EIAs.
abstract: BACKGROUND
  Following the recognition of a measles case in a hospital in The Netherlands, health care workers (HCW) from the premises were screened by a commercial enzyme immunoassay (EIA) for measles IgG to identify persons at risk for measles. At least 10% of the HCW were tested measles IgG-negative. As this was considered an unusually high proportion, we hypothesized suboptimal sensitivity of EIAs, especially in medical personnel that had vaccine-induced immunity rather than antibodies resulting from natural infection.
  
  
  OBJECTIVE
  To determine (vaccine-induced) measles immunity in HCW, using different EIAs compared to the plaque reduction neutralization (PRN) test, the best surrogate marker for vaccine efficacy and immune protection.
  
  
  METHODS
  Sera from HCW were tested for measles IgG antibodies in three commercial EIAs, in a bead-based multiplex immunoassay (MIA) and in the PRN test, and evaluated against age and vaccination history of the HCW.
  
  
  RESULTS
  Of the 154 HCW, born between 1960 and 1995, 153 (99.4%) had protective levels of measles antibodies (PRN> 120mIU/ml). The three EIAs failed to detect any measles IgG antibodies in approximately 10% of the HCW, while this percentage was approximately 3% for the MIA. Negative IgG results rose to 19% for individuals born between 1975 and 1985, pointing to an age group largely representing vaccinated persons from the first measles vaccination period in The Netherlands.
  
  
  CONCLUSIONS
  The results show limitations in the usefulness of current EIA assays for determining protective measles antibodies in persons with a vaccination history.
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands; Laboratory Medical Microbiology, Tergooi Hospital, Hilversum, The Netherlands.
authors.forename: J Wendelien
authors.initials: JW
authors.lastname: Dorigo-Zetsma
authors.affiliation: Department of Medical Microbiology, Bronovo Hospital, The Hague, The Netherlands.
authors.forename: Maurine A
authors.initials: MA
authors.lastname: Leverstein-van Hall
authors.affiliation: Department of Medical Microbiology, Bronovo Hospital, The Hague, The Netherlands.
authors.forename: Joyce
authors.initials: J
authors.lastname: Vreeswijk
authors.affiliation: Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Jutte J C
authors.initials: JJ
authors.lastname: de Vries
authors.affiliation: Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Ann C T M
authors.initials: AC
authors.lastname: Vossen
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands.
authors.forename: Hinke I
authors.initials: HI
authors.lastname: Ten Hulscher
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Kerkhof
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands.
authors.forename: Gaby P
authors.initials: GP
authors.lastname: Smits
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands.
authors.forename: Wilhelmina L M
authors.initials: WL
authors.lastname: Ruijs
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands; Department of Viroscience, Erasmus University MC, Rotterdam, The Netherlands.
authors.forename: Marion P G
authors.initials: MP
authors.lastname: Koopmans
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands. Electronic address: rob.van.binnendijk@rivm.nl.
authors.forename: Robert S van
authors.initials: RS
authors.lastname: Binnendijk
mesh_terms: D000328:Adult; D000367:Age Factors; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D008297:Male; D008457:Measles / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D008458:Measles Vaccine / Q000627:therapeutic use; D008459:Measles virus / Q000276:immunology / Q000302:isolation & purification; D008875:Middle Aged; D009426:Netherlands; D009500:Neutralization Tests; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D008458:Measles Vaccine
keywords: Antibody; Health care worker; Measles; Neutralization; Protection; Vaccination