[Humoral immune response to the capsular polysaccharide of Neisseria meningitidis serogroup C in an antimeningococcal BC vaccination trial in Antioquia, Colombia].

As a complement to studying humoral immune response to the proteins of an antimeningococcal vaccine (VA-MENGOC-BC) against serogroups B and C, the humoral immune response to polysaccharide C of the vaccine was also evaluated in 142 children from 1 to 5 years of age in an area of the Department of Antioquia, Colombia. Paired pre-(T0) and post-vaccination (T1) sera were tested for IgG response by means of ELISA and for serum lytic capacity against a strain of serogroup C by means of the bactericidal antibodies test (BAT). Response to the vaccine was statistically significant (P < 0.01) by both techniques. PAB demonstrated seroconversion (T1/T0 > or = 4) in 88% (95% confidence interval, CI95%: 80% to 95%) of all those who were seronegative before vaccination. The proportion of seroconversion in children 2, 3, and 4 years of age was 86% or more. Of all the sera tested with ELISA, 93% (CI95%: 89% to 97%) showed response to the vaccine (T1/T0 > or = 2), and 98% (CI95%: 94% to 100%) of the subjects with T0 < or = 500 U/mL seroconverted. In this sample, the vaccine stimulated a specific and protective response as measured by ELISA and BAT, the latter test being utilized to evaluate protection status.