TABLE 1.

Comparison of HAI and MN assay resultsa

MN test and resultNo. of results
HAI1:40bHAI1:20c
++
MN1:40b
    +38194413
    −164461
MN1:20c
    +38244418
    −159456
  • a +, evidence of seroconversion. −, absence of seroconversion. Convalescent titer cutoffs for positivity were 1:40 or 1:20 in pH1N1 index cases (n = 24) and their household contacts (n = 98). HAI, hemagglutination inhibition assay. MN, microneutralization assay. MN1:40 versus HAI1:40, kappa = 0.66; MN1:40 versus HAI1:20, kappa = 0.72; MN1:20 versus HAI1:40, kappa = 0.59; MN1:20 versus HAI1:20, kappa = 0.64.

  • b 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.

  • c 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.