Loading...
The first effective meningococcal (Men) vaccines, which consisted of capsular polysaccharides from meningococci of the respective serogroups, are not immunogenic in children aged <2 years. Conjugation of the polysaccharides to a protein carrier has resulted in vaccines (Men, as well as Haemophilus influenzae type b [Hib] and Streptococcus pneumoniae) that are immunogenic even in young infants. In a partially industry-supported, phase IV, open-label, controlled trial conducted in the U.K. and Malta, researchers compared two such vaccines — MenC-CRM (which uses CRM97 protein, a nontoxic mutant of diphtheria toxoid) and MenC-TT (a MenC polysaccharide–tetanus toxoid formulation) — to determine the most-effective serogroup C Men conjugate vaccination schedule.
The 509 infant vaccinees were randomized in a 10:10:7:4 ratio to receive a single priming dose of MenC-CRM at age 3 months; two doses of MenC-CRM, at 3 and 4 months; MenC-TT at 3 months; or no Men priming dose. All participants received Hib–MenC-TT at 12 months. Blood samples were taken at 5, 12, 13, and 24 months to determine MenC bactericidal antibody titers.
At 13 months, the immunogenicity of one priming dose of MenC-CRM was superior to that of two MenC-CRM doses; the immunogenicity of MenC-TT after a single priming dose was superior to that seen in either MenC-CRM group. At 24 months, the titers had dropped in all groups; they remained protective (≥1:8) in 82% of the Men-TT group compared with only 20% and 31% in the two- and one-dose MenC-CRM groups, respectively.
Pace D et al. Immunogenicity of reduced dose priming schedules of serogroup C meningococcal conjugate vaccine followed by booster at 12 months in infants: Open label randomised controlled trial. BMJ 2015 Apr 1; 350:h1554. (http://dx.doi.org/10.1136/bmj.h1554)
Comment
Although many other countries recommend MenC vaccination in infancy, the U.S. does not. Countries where MenC vaccination is given routinely vary as to the number and timing of doses. If the U.S. recommendations change, these findings support a single infant priming dose, as is done currently in the U.K.