Evaluation of the time resolved fluorescence immunoassay (TRFIA) for the detection of varicella zoster virus (VZV) antibodies following vaccination of healthcare workers

S. L.R. McDonald*, P. A.C. Maple, N. Andrews, K. E. Brown, K. L. Ayres, F. T. Scott, M. Al Bassam, A. A. Gershon, S. P. Steinberg, J. Breuer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Determination of varicella zoster virus (VZV) immunity in healthcare workers without a history of chickenpox is important for identifying those in need of vOka vaccination. Post immunisation, healthcare workers in the UK who work with high risk patients are tested for seroconversion. To assess the performance of the time-resolved fluorescence immunoassay (TRFIA) for the detection of antibody in vaccinated as well as unvaccinated individuals, a cut-off was first calculated. VZV-IgG specific avidity and titres six weeks after the first dose of vaccine were used to identify subjects with pre-existing immunity among a cohort of 110 healthcare workers.Those with high avidity (≥60%) were considered to have previous immunity to VZV and those with low or equivocal avidity (<60%) were considered naive. The former had antibody levels ≥400. mIU/mL and latter had levels <400. mIU/mL. Comparison of the baseline values of the naive and immune groups allowed the estimation of a TRFIA cut-off value of >130. mIU/mL which best discriminated between the two groups and this was confirmed by ROC analysis. Using this value, the sensitivity and specificity of TRFIA cut-off were 90% (95% CI 79-96), and 78% (95% CI 61-90) respectively in this population. A subset of samples tested by the gold standard Fluorescence Antibody to Membrane Antigen (FAMA) test showed 84% (54/64) agreement with TRFIA.

Original languageEnglish
Pages (from-to)60-65
Number of pages6
JournalJournal of Virological Methods
Volume172
Issue number1-2
DOIs
Publication statusPublished - Mar 2011

Bibliographical note

Funding Information:
SLRM was funded by Bart's and the London special trustees . JB receives funding from the NIHR UCLH/UCL Comprehensive Biomedical Research Centre .

Keywords

  • Antibody
  • Fluorescent Antibody to Membrane Antigen
  • Time-resolved fluorescence immunoassay
  • VOka vaccine
  • Varicella zoster virus

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