Table 4.

 Sensitivity and specificity determination for the H7 HA2 RRT PCR in comparison to (a) VI and (b) M gene RRT PCR, using 259 and 297 poultry swabs respectively

(a) Sensitivity [34/(34 + 0) = 100%], specificity [202/(23 + 202) = 89·8%]
n = 259	Virus isolation		Total
	+	−
H7 HA2+	34*	23**	57
RRT PCR−	0	22 + 180 = 202	202
Total	34	225	259
(b) Sensitivity [62/(62 + 3) = 95·4%], specificity [227/(5 + 227) = 97.9%]
n = 297	M gene RRT‐PCR		Total
	+	−
H7 HA2+	62***	5†	67
RRT PCR−	3††	47 + 180 = 227	230
Total	65	232	297

Normal type numbers indicate specimens from experimentally infected (H7N1) poultry and italic numbers indicate specimens from farmed chickens.

*Ct range: 23·32–35·29; Mean 29·33; Median 29·36.

**Ct range: 27·55–37·91; Mean 33·68; Median 34·19.

***Ct range: M gene RRT PCR: 21·70–38·65; Mean 31·24; Median 31·38. H7 HA2 RRT PCR: 23·32–38·31; Mean 31·12; Median 30·78.

†Ct values: 34·86, 35·01, 37·02, 37·15, 37·18.

††Ct values: 35·48, 37·07, 37·21.