Invasive Meningococcal Infections Despite Immunization

Background:  Meningococcal conjugate (MCV4) and polysaccharide (MPSV4) vaccines have been recommended for persons aged 11-18 years or at increased risk of invasive meningococcal disease. Although MCV4 is immunogenic, its clinical efficacy has not been established, and cases in immunized persons are known to occur.

Objectives:  Characterize invasive meningococcal disease in previously-immunized persons.

Methods:  We reviewed reported invasive meningococcal disease that occurred from 2006 -- 2010 in California residents who had received at least one dose of meningococcal vaccine.

Results:  Of 718 total cases, 24 occurred in previously-vaccinated persons; 9 had a vaccine-preventable serogroup: Y (5), C (3), W-135 (1).  The remaining 15 were of serogroup B (11), ungroupable (3) or unknown (1).  The serogroup distribution was not statistically different between immunized and non-immunized cases of the same age.  Of the patients infected with a vaccine-preventable serogroup, 5 had received MCV4, 2 had received MPSV4, and 2 vaccine types were unknown.  All 5 MCV4 recipients were previously healthy males whose median age was 19 years (18-21 years); 3 were military recruits, 2 were college students.  The median time from immunization to disease onset was 151 days (9 days-3 years).  Four had nonfatal serogroup Y infections, 3 with meningococcemia and/or meningitis (3) or septic arthritis (1).  A fatal case had serogroup C meningococcemia and meningitis.  The two MPSV4 recipients had serogroup C (1) or Y (1) infections.

Conclusions:  Although rare, breakthrough cases of invasive meningococcal disease occur after immunization of healthy individuals.  MCV4 failures occurred most often with serogroup Y, the least immunogenic serogroup of MCV4 for adolescents and adults.  Because of concerns about waning immunity, ACIP recently recommended an additional booster dose of MCV4. This report provides the largest population-based review of breakthrough meningococcal disease.