Q: Why was meningococcal serogroup B not included in the initial meningococcal vaccines (MenACWY)?
A: Prevention of meningococcal disease by vaccines has relied on antibodies directed against the serogroup-specific polysaccharides. Conjugation of the polysaccharide from the capsule with a protein carrier enhances immunogenicity. The polysaccharide capsule of Neisseria meningitides serogroup B is poorly immunogenic even with protein conjugation. The polysaccharide of serogroup B meningococcus is similar to certain human glycoproteins, such as intracellular adhesion molecules. This similarity to human molecules likely explains the poor immunogenicity. An alternate approach to vaccine development required using meningococcal B proteins as the antigens.
Q: What is the difference between a Category A and Category B recommendation from the Advisory Committee on Immunization Practices (ACIP)?
A: Vaccines with a Category A recommendation are recommended routinely for the entire population or for a selected portion of the population based on age or increased risk.
Vaccines with a Category B recommendation are not routinely recommended. ACIP uses Category B recommendations for vaccines licensed by the Food and Drug Administration, i.e., proven safe and effective, when an individual in consultation with his or her medical provider believes it is prudent for the individual to receive the vaccine. This previously was called a “permissive” recommendation.
Q: Does the difference in the recommendation type affect payment for the vaccine?
A: The Affordable Care Act requires federal and commercial insurance to pay for all vaccines recommended by ACIP, regardless of whether it is a Category A or Category B recommendation.
Q: Why isn’t MenB routinely recommended for adolescents and young adults as is the case for MenACWY?
A: There is an increased incidence in meningococcal disease in individuals 14-22 years of age compared to younger children and older adults. Meningococcal serogroups C and Y were the predominant meningococcal strains causing disease in adolescents and young adults. There was an even greater incidence of serogroups C and Y in college students compared to the general population, especially first-year college students living in dorms and those with other exposure factors such as smoking/passive smoke or frequenting bars. Serogroup B incidence in adolescents and young adults compared with other age groups is not markedly different as was the case for serogroups C and Y.
Even with the recent serogroup B meningococcal outbreaks on college campuses, college students are not at an increased risk for serogroup B meningococcal disease compared to the general population.
Q: Does the recent New England Journal of Medicine article (http://www.nejm.org/doi/full/10.1056/NEJMoa1514866) noting that only 66% of immunized students developed seroprotective antibodies to the meningococcal strain causing the university outbreak impact the AAP recommendations for MenB vaccines?
A: The new information does not change the recommendations in the policy statement. However, it will impact how pediatricians discuss the MenB vaccine with patients and families, and how they would respond following a definite exposure to someone with serogroup B meningococcal disease.
The findings were not completely unexpected. The protein antigens from the meningococcal strain in the university outbreak were similar to but not identical to the protein antigens in the vaccine.
In the study, only 66% of immunized students developed antibodies directed against the outbreak strain antigens, and they were low titers. However, nearly 100% of the students developed antibodies directed to meningococcal strains whose antigens were used in the vaccine. This confirms the prior concern that MenB vaccines may not cause development of seroprotective antibodies in individuals when the circulating strain has protein antigens that differ from the administered MenB vaccine’s protein antigens.
At licensure, there was an estimate that the MenB vaccine used during the outbreak would provide protection against 91% of circulating serogroup B meningococcal strains in the U.S. Further studies will be required to determine whether this estimate is accurate.
Regardless of immunization status (MenACWY and/or MenB vaccines), individuals with confirmed high-risk exposures (as defined in the Red Book) to a person with meningococcal invasive disease due to any serogroup need to receive usual post-exposure chemoprophylaxis.
Please see related article "AAP policy outlines when to use meningococcal B vaccines."