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Table 3 Specificities in external controls (n = 4275) and sensitivities in time intervals in reference to the onset of cough in pertussis cases (n = 46) of single IgA and IgG concentrations (see Figure 2). Geometrical Mean Concentrations (GMC) and number of samples are indicated.

From: Sensitivity and specificity of single IgA and IgG antibody concentrations for early diagnosis of pertussis in adults: an evaluation for outbreak management in public health practice

Level (U/ml)a Specificity external controls Sensitivity (%) in time intervals with reference to the onset of cough
   -21 to 0 days 1 to 14 days 15 to 21 days 22 to 87 days 1 to 87 days
IgA       
24 90.0% 33 100 100 97 98
40 95.0% 33 63 82 95 90
52 97.5% 17 63 82 92 88
74 99.0% 17 63 64 78 75
GMC (U/ml)   11 60 136 212 177
IgG       
27 90.0% 33 75 100 97 95
41 95.0% 33 75 91 95 93
65 97.5% 33 50 82 94 87
90 99.0% 33 38 82 86 81
100b 99–100% 33 38 82 84 80
GMC (U/ml)   8 48 390 506 391
No. samples   6 8 11 64 83
  1. a Levels are obtained from the estimation of optimal cut-off values in Figure 2.
  2. b Used by the National Institute for Public Health and the Environment in The Netherlands for surveillance.