Diagnostic agreement between oral fluid and serum assays to detect
measles IgG antibody in healthcare providers
Abstract
Background: An easy-to-use, low-risk, and non-invasive method to detect
the measles antibody, such as oral fluid (OF) assay, is required in the
clinic. Methods: We tested the measles IgG antibody in the serum and OF
of healthcare providers enrolled from four hospitals in Beijing, China,
between March and December in 2018. We also tested the pre- and
post-vaccination antibodies in selected participants. Serum and OF
antibodies were detected by indirect and capture EIA, respectively.
Results: Overall, 550 pairs of serum and OF samples were collected from
495 participants, including 55 pre- and post-vaccination pairs. ROC
analysis showed a high diagnostic value of OF assay (AUC = 0.84, P
< 0.01). The positive and negative consistency rates with
serum were 90.0% and 67.9%, respectively (κ = 0.53). The sensitivity
and specificity of the OF assay were 90.2% and 67.9%, respectively.
Positive measles IgG rates in paired serum and OF were 83.6% and
80.2%, respectively. There were no significant differences in the OF
assay between different genders (P > 0.05) and vaccination
histories (P = 0.12). Statistically significant differences were
identified in participants with different histories of measles contacts
and measles infections. In different age groups, the positive OF measles
antibody rates ranged from 71.6% to 89.7% (P = 0.01), with
participants ≥ 40 years old having the highest positive rate. After
vaccination, increased measles antibody levels and positive rates were
observed by both serum and OF assays. Conclusions: There was a
relatively high agreement between serum and OF measles antibody assays.