Measurement of Haemophilus Influenzae Type A Capsular Polysaccharide Antibodies in Cord Blood Sera

We measured anti-Haemophilus influenzae type a capsular polysaccharide serum immunoglobulin G antibodies in cord blood sera from Mexican (n = 68) and Chilean mothers (n = 72) by enzyme-linked immunosorbent assay. Measurable antibodies were found in 79.3% of samples. Immunoglobulin G antibodies correlated with serum bactericidal activity (r = 0.66). This enzyme-linked immunosorbent assay can be used for the evaluation of adaptive immune responses to Haemophilus influenzae type a and serosurveillance studies in populations at risk.