A majority of children were not protected from Neisseria meningitidis serogroup C 5 years after receiving a combined Haemophilus influenzae type b–N. meningitidis serogroup C–tetanus toxoid conjugate vaccine or other MenC combination vaccines, according to Dr. Juan Carlos Tejedor of Hospital Universitario de Móstoles, Madrid, and his associates.

A total of 530 children approximately 6 years old were included in the study. Participants received vaccinations at 2, 4, and 6 months, and received a booster vaccination at 11-18 months. Patients were separated into four groups, receiving either Hib–MenC plus a 10-valent pneumococcal nontypeable H. influenzae protein D conjugate vaccine (PHiD-CV), Hib–MenC plus 7-valent cross-reacting material 197 (CRM197) conjugate vaccine (7vCRM), MenC plus CRM, or MenC plus tetanus toxoid vaccinations. MenC antibody titers were measured with a serum bactericidal antibody assay using rabbit complement (in other words, rabbit SBA [rSBA]).

The rate of seropositivity for rSBA–MenC titers ranged from 24% to 40%. All groups maintained a seropositivity rate of at least 98.5% for anti-Hib polyribosylribitol phosphate antibodies, and at least 72.8% of children maintained seropositivity for hepatitis B.

“The low MenC titers at 5 years after vaccination suggested that individuals may no longer be protected or contribute to herd immunity,” the investigators noted.

Find the full study in Clinical and Vaccine Immunology (2016 Jul. doi: 10. 1128/CVI.00057-16 ).