VAIL, COLO. – When the Advisory Committee on Immunization Practices meets in late October to review the recently approved meningococcal groups C and Y and Haemophilus influenzae type b tetanus toxoid conjugate for infant immunization, it will not recommend the vaccine’s routine use in all infants, Dr. Marsha S. Anderson predicted.
The Hib-MenCY-TT vaccine is marketed as MenHibrix.
Dr. Marsha S. Anderson
For the past couple of years, the ACIP Working Group for Meningococcal Disease has been discussing whether infants should be routinely vaccinated against meningococcal disease. The group indicated at its June 2012 meeting that the time isn’t right for such a practice recommendation, in spite of the Food and Drug Administration’s approval the very same month of MenHibrix as the first-ever meningococcal vaccine licensed for infant immunization starting as early as age 6 weeks.
Routine infant meningococcal vaccination is a complicated issue, with arguments for and against, and there is no right answer, Dr. Anderson said at a conference on pediatric infectious diseases, which was sponsored by Children’s Hospital Colorado in Aurora. But when she ran down the pros and cons, she caused a seismic shift in audience opinion.
At the outset of her talk, when she polled her audience to see who favored routine meningococcal vaccination in infancy given the current licensed vaccines, two-thirds of the audience signaled via electronic clicker that they were for it. Afterward, however, 82% were opposed.
Meningococcal disease is the top cause of bacterial meningitis in children and young adults in the United States. Outbreaks cause widespread public fear and panic. The mortality rate of meningococcal meningitis is 10%, with death typically coming within 24-48 hours after symptom onset. Up to 20% of survivors of bacterial meningitis have learning disabilities, permanent hearing loss, or other serious sequelae, noted Dr. Anderson of the University of Colorado at Denver, Aurora.
Arguments supporting routine infant immunization include the fact that the meningococcal disease incidence rate is much higher in infants than in other age groups. The current ACIP recommendation for meningococcal conjugate vaccination, which calls for routine vaccination at age 11-12 years with a booster dose at age 16, doesn’t address that epidemiologic reality. Moreover, the MenHibrix vaccine was shown to be safe and effective in prelicensure studies.
"And as physicians and nurses, we all want to protect every single child against this devastating disease," she observed.
On the con side, 50%-60% of all infant disease in the United States involves serogroup B meningococcus – and protection against serogroup B isn’t included in any licensed U.S. vaccine. This is not for lack of trying. The problem is that the polysaccharide capsule of serogroup B meningococcus is poorly immunogenic. Vaccines that were developed in New Zealand, Cuba, and Australia to protect against serogroup B in those isolated nations turned out to be strain specific and don’t protect against U.S. strains.
On a more optimistic note, promising studies are underway in other countries using vaccines made from multiple strains and with several antigenic targets. It’s quite likely that an effective serogroup B–protective vaccine will eventually get here, according to Dr. Anderson.
Another argument against routine immunization in infancy is that the annual incidence rate of meningococcal disease in the United States is at an all-time low, with an incidence rate only one-fifth that in the early 1980s. A Centers for Disease Control and Prevention modeling analysis estimated that routine administration of a four-dose infant series of meningococcal conjugate vaccine in the current low-incidence era might prevent 44 cases of meningococcal disease annually. The number of infants who would need to be vaccinated in order to prevent one case was estimated at 76,000. The number needed to be vaccinated in order to prevent one death was put at 642,000. That’s not very cost effective.
There also are practical stumbling blocks standing in the way of routine infant immunization. MenHibrix is given in a four-dose series at 2, 4, 6, and 12 months.
"I’m guessing everybody is shuddering at trying to figure out how to fit that into the current vaccine schedule," Dr. Anderson guessed.
Actually, though, it would not necessarily require any additional shots, she noted. It could be administered in a three-shot visit together with DTaP/IPV/Hep B (Pediatrix) and PCV13 (Prevnar13), although that necessitates switching from other combination Hib products.
Another option is the vaccination of toddlers with MenACWY-D (Menactra), a two-dose series given at 9 and 12 months. The difficulty here is that at present there is no routine office visit at 9 months of age. Plus, most kids won’t be protected against meningococcus until the second dose, so they will remain vulnerable to the infection through most of infancy.