TABLE 2.

Comparison of HAI and MN assays to RT-PCR for pH1N1 diagnosisa

Assay and result% Sensitivityb (95% CI)No. of cases with RT-PCR result
PositiveNegative
MN1:40c82.8 (70.1, 91.0)
    +489
    −1055
‡MN1:20d84.5 (72.1, 92.2)
    +4913
    −951
HAI1:40c60.3 (46.6, 72.7)
    +354
    −2360
HAI1:20d70.7 (57.1, 81.5)
    +417
    −1757
  • a HAI, hemagglutinin inhibition assay. MN, microneutralization assay. CI, confidence interval. +, evidence of seroconversion. −, absence of seroconversion. MN1:40 versus RT-PCR, kappa = 0.69; MN1:20 versus RT-PCR, kappa = 0.64; HAI1:40 versus RT-PCR, kappa = 0.54; HAI1:20 versus RT-PCR, kappa = 0.60.

  • b Serological method sensitivity for detection of RT-PCR confirmed cases.

  • c Seroconversion 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.

  • d Seroconversion 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.