Table 2.

Correlation between ELISA, flow assay, and killing assay using antisera from adults vaccinated with pneumococcal PS or conjugate vaccine

VaccineSerotypenbCorrelation between assaysa
Flow and killingELISA and killingFlow and ELISA
rPfSdrPSrPS
23-valent PS6A230.580.010.160.170.011.340.600.010.48
6B230.870.0010.560.540.050.540.490.050.32
19F230.06NSe0.100.22NS0.550.14NS0.44
Bivalent conjugate23F46c0.910.010.470.870.011.340.980.0010.64
Tetravalent conjugate6B340.770.0010.410.900.0011.620.790.0010.76
19F400.650.010.300.870.011.070.650.050.37
23F400.790.0010.610.910.0011.330.750.0010.84
  • a The correlation coefficient (r) was calculated by Pearson's bivariate linear correlation analysis.

  • b n is the total number of analyzed antisera per vaccine. For the PS vaccine, only postvaccination antisera were analyzed, whereas for the conjugate vaccines pre- and postvaccination antisera were combined for correlation analysis.

  • c For the killing assay, titers were obtained for 14 antisera only. Therefore, correlations between killing assay and ELISA flow assay and ELISA were calculated for these corresponding 14 antisera.

  • d The slope (S) of the fitted linear curve, Y = Sx + b, was calculated by linear regression analysis.

  • e NS, not significant

  • f P is less than the values given.