By: Dr. Geoffrey Modest
The FDA has recently approved the use of serogroup B meningocococcal vaccines
In brief:
–current meningococcal vaccines do not include serogroup B because the capsule is not immunogenic, though serogroup B is a very common cause of meningococcal disease: of the 500 cases of meningococcal disease in the US in 2012, 160 were caused by serogroup B. The current vaccines only includes serogroups A, C, Y, and W-135.
–the new vaccines target outer membrane proteins with some success, though there are many different outer membrane proteins and they are not consistently present in different serogroup B strains.
–the FDA has now approved 2 different vaccines (Trumenba and now Bexsero), for those aged 10-25 yo. ACIP (The Advisory Committee of Immunization Practices) has not yet published a recommendation for these vaccines, though in Europe Bexsero is given for those >2 months old as a series of 3 intramuscular doses and can be given concomitantly with the other vaccines. At age 10, the recommendation is 2 doses more than 1 month apart.
–for Boxsero, there have been 3 studies of 2600 adolescents finding 62-88% had antibodies that killed 3 different outer capsule strains of serotype B. These 3 strains are representative of strains that cause most serogroup B infections in the US
–adverse effects in 5000 participants were mostly pain/swelling at injection site, headache, diarrhea, myalgia, arthralgia, fatigue and chills. Additionally, the vaccine was given to 15,000 students at 2 universities where there were outbreaks of serogroup B meningococcal infections, without evident problems.
So, given that these are the only vaccines covering serogroup B infections, the FDA has given them “accelerated approval” to get them to market sooner. But there have not been studies showing clinical efficacy, just that they seem to promote killer antibodies in the lab. We will see what ACIP recommends, but these vaccines may be really important in preventing a potentially very serious disease.