[Humoral immune response to the proteins of an antimeningococcal BC vaccine in a trial carried out in Antioquia, Colombia].

Abstract

This study evaluated the humoral response to protein components of the Cuban-produced vaccine against serogroups B and C meningococcus, VA-MENGOC-BC, in adults and children 1 to 5 years old. The trial was conducted in an area of the Department of Antioquia, Colombia, in which an elevated incidence of meningococcal disease had been recorded. The serum anti-vaccine-protein response was studied before (T0) and after (T1) vaccination by means of enzyme-linked immunosorbent assay (ELISA), and lytic capacity was evaluated through the bactericidal antibodies test (BAT). The ELISA was performed before and after vaccination on the sera of 407 adults and 213 children. Lytic capacity against Cuban meningococcal strain B:4:P1.15 was studied with BAT in paired sera from 90 adults and 114 children. The two techniques showed a statistically significant response (P < 0.01) to the vaccine, in both adults and children. Of the total number of subjects tested with ELISA, 81% showed an immune response to the vaccine (T1/T0 > or = 2) (95% confidence interval, CI95%: 78% to 84%); among children, immune response was 91% (CI95%: 87% to 94%). All the children 1 year of age (n = 7) responded. Seroconversion (T1/T0 > or = 4), as shown by ELISA, was 80% among adults (CI95%: 73% to 86%) and 90% among children (CI95%: 83% to 100%). BAT demonstrated seroconversion in 85% (CI95%: 78% to 92%) of subjects who had been seronegative before vaccination, 85% of the adults (CI95%: 76% to 95%) and 84% of the children (CI95%: 72% to 96%). Seroconversion among children 3 and 4 years of age was 80%. The group of sera from children 1, 2, and 5 years old available for study with BAT was too small for meaningful statistical analysis; all of them seroconverted. In 20 sera chosen randomly for study of their bactericidal activity against all the strains isolated from patients in Colombia (B:4:P1.15, B:8:P1.nt, and two strains of serogroup C), seroconversion was found in all 20 cases. These results give reason to think that vaccination in this group produced an effective immune response, as measured serologically, and this belief is corroborated in practice by the lack of any cases of meningococcal disease through September 1994 among the people vaccinated.