TABLE 2.

Comparison of HAI and MN assays to RT-PCR for pH1N1 diagnosis^a

Assay and result	% Sensitivityb (95% CI)	No. of cases with RT-PCR result
		Positive	Negative
MN1:40c	82.8 (70.1, 91.0)
+		48	9
−		10	55
‡MN1:20d	84.5 (72.1, 92.2)
+		49	13
−		9	51
HAI1:40c	60.3 (46.6, 72.7)
+		35	4
−		23	60
HAI1:20d	70.7 (57.1, 81.5)
+		41	7
−		17	57

^aHAI, hemagglutinin inhibition assay. MN, microneutralization assay. CI, confidence interval. +, evidence of seroconversion. −, absence of seroconversion. MN_1:40 versus RT-PCR, kappa = 0.69; MN_1:20 versus RT-PCR, kappa = 0.64; HAI_1:40 versus RT-PCR, kappa = 0.54; HAI_1:20 versus RT-PCR, kappa = 0.60.

^bSerological method sensitivity for detection of RT-PCR confirmed cases.

^cSeroconversion was defined as an acute-phase serum titer of <1:10 with a convalescent titer of ≥1:40 or a significant increase (≥4-fold) in antibody titers between the two sera.

^dSeroconversion was defined as an acute-phase serum titer of <1:10 with a convalescent titer of ≥1:20 or a significant increase (≥4-fold) in antibody titers between the two sera.