The first pentavalent vaccine approved against all five major serogroups of meningococcal disease has clinicians evaluating the optimal timing for vaccination, according to a new analysis.
Vaccines have helped greatly reduce the rate of invasive meningococcal disease among adolescents over the past 20 years, and the new formulation that covers all main types of the bacteria could help improve vaccination coverage and drive infection rates even lower, reported the researchers led by senior author Gregory Zimet from the department of pediatrics at the Indiana University School of Medicine in Indianapolis, Indiana.
The five main serogroups — labelled A, B, C, W, and Y — cause most of the disease set off by the bacteria Neisseria meningitidis. It is a rare but serious illness that mostly affects adolescents and young adults.
Meningitis often presents with nonspecific symptoms and can progress to serious illness and even death within hours.
"Clinical features of invasive meningococcal disease, coupled with its unpredictable epidemiology, suggest that vaccination is the best strategy for preventing associated adverse outcomes," the researchers reported.
Before the introduction of vaccines in 2005, the incidence of disease in the United States ranged from 0.5-1.1 cases per 100,000 people, with ≥ 10% of cases being fatal.
The Quadrivalent Vaccine
In 2005, the first quadrivalent meningococcal vaccine, covering serogroups ACWY, was approved in the United States and recommended for routine use in 11- and 12-year-olds, followed by a 2010 booster recommendation at age 16 years.
Between 2006 and 2017, the estimated incidence among 11- to 15-year-olds dropped by > 26% each year.
For those aged 16-22 years, the incidence dropped even further by > 35% per year between 2011 and 2017 after the booster was introduced.
Rates also fell in other groups that had not been vaccinated, such as in infants and adults, suggesting possible herd protection after the vaccines.
With Serogroup B
By 2015, a vaccine covering serogroup B was also approved. However, it was not added to the routine vaccination schedule and was subject to shared clinical decision-making between clinicians and patients.
The B vaccine has been less successful, reported the researchers, who said this is likely because uptake was much lower due to it not being part of the routine schedule.
Today, serogroup B now makes up a greater proportion of meningitis cases. Before the vaccines were introduced, it accounted for about one third of cases, and now it is the cause of about half of all cases.
Two Doses with a Boost?
In October, the US Food and Drug Administration approved the first pentavalent vaccine against all five major serogroups, which the authors of the analysis said, "may help optimize the existing US adolescent meningococcal vaccination platform".
A modelling study suggested that the current vaccination schedule of two doses each of the vaccines would prevent 165 cases of meningitis over 10 years. However, a two-dose pentavalent vaccine at age 11 years plus a booster at age 16 years would not only simplify the process and reduce the number of injections required but would also increase the number of cases prevented to 256.
"Use of pentavalent vaccines yields the potential to build on the success of the incumbent program, raising B vaccination coverage by simplifying existing recommendations and decreasing the number of injections required," the researchers reported, thus "…reducing the clinical and economic burden of meningococcal disease."