Development of antibodies against tetravalent meningococcal polysaccharides in revaccinated complement‐deficient patients
Individuals deficient in C3 or a late complement component are susceptible to recurrent meningococcal infections. Since they experience meningococcal episodes mostly with uncommon meningococcal serogroups, vaccination with a tetravalent vaccine containing A, C, Y and W135 polysaccharides has been suggested. We vaccinated a cohort of two C3 and 17 late complement component‐deficient (LCCD) patients, revaccinated them 7 years later and investigated the development of their IgG antibodies to the capsular polysaccharides of the meningococcal vaccine. Seven years after the first vaccination levels of IgG antibodies declined compared with the levels present at 6 months after the first vaccination, but were still at least four times higher than before vaccination. Levels of antibodies to Y polysaccharide in serum of complement‐deficient patients were rather low but they did not differ significantly from those in serum of healthy non‐related controls (P = 0.07). Three months after the second vaccination IgG antibodies against all polysaccharides increased, exceeding those measured at 6 months after the first vaccination. In the 8 years of observation after the first vaccination two new meningococcal infections with strains related to the vaccine (serogroup Y strains) occurred in two patients, 3.5 and 5 years after the first vaccination. Our findings show that high IgG antibody levels against the tetravalent meningococcal polysaccharide vaccine were reached after revaccination of two C3 and 17 LCCD individuals 7 years after the first vaccination. Whether revaccination should be required within a period shorter than 7 years is discussed, since two vaccinees developed meningococcal disease to vaccine serogroup Y.