Aggregate reverse cumulative distribution curves of anti-PS IgG concentrations measured in pediatric sera after immunization with the Prevenar vaccine for comparison of the WHO non-22F ELISA and the WHO 22F ELISA, both of which were performed at ICH, with the GSK 22F ELISA, which was performed at GSK (study C). In addition to our standard comparison of the WHO non-22F ELISA (threshold, 0.35 μg/ml) with the two 22F ELISAs (GSK 22 [dotted lines] and WHO 22F [blue dashed line]), a comparison of the WHO 22F ELISA (by use of a 0.35-μg/ml threshold) and the GSK 22F ELISA was also performed (red dashed line).