PHILADELPHIA, PA—Substantial proportions of children who received the MenACWY-CRM conjugate vaccine between the ages of 2 and 10 years continued to have persistent antibodies against all four serogroups, with robust increases in antibody titers after a booster dose 5 years following the primary vaccination series, according to data presented at IDWeek 2014.
These increases were observed regardless of the previous number of doses, demonstrating an anamnestic response, said Stanley L. Block, MD, of the Kentucky Pediatric and Adult Research Center, Bardstown, KY.
The Advisory Committee on Immunization Practices recommends that quadrivalent MenACWY-CRM conjugate vaccines be used in children up to 10 years of age at risk of invasive meningococcal disease due to Neisseria meningitidis infection and in all children 11–12 years of age, with a booster dose at 16–18 years of age.
The study, conducted at 22 U.S. sites between May and October 2013, examined the persistence of serum bactericidal activity with human complement (hSBA) antibodies induced by the vaccine following the booster dose in two groups of 7- to 10-year-old children after 1 (n=101) or 2 (n=73) doses as 2- to 5-year-olds and one group of 11- to 15-year-old children after 1 dose (n=66). Subjects of a similar age (eg, 7–10 years old [n=120] or 11– 15 years old [n=101]) who had not previously received a meningococcal vaccine served as vaccine-naïve age-matched controls.
Results showed that “higher proportions of previously vaccinated participants had hSBA titers ≥8 compared with vaccine-naïve control subjects across serogroups and age groups,” Dr. Block reported. “At 5 years, hSBA geometric mean titers (GMTs) against all four serogroups were higher in previously vaccinated participants compared with age-matched vaccine-naïve controls.”
Compared with controls, GMTs against serogroups C, W, and Y were twofold to threefold greater in the subjects who were vaccinated and, in children 7 to 10 years of age, antibody persistence appeared to be similar whether previously vaccinated with 1 or 2 doses of the MenACWY-CRM vaccine.
He noted that 1 month after a booster dose of the vaccine at 5 years, “levels of bactericidal antibodies increased substantially against all serogroups in the previously vaccinated subjects.” A total of 99% to 100% achieved hSBA titers ≥8 against all four serogroups in both the 7- to 10- and 11- to 15-year-old age groups, compared with 75% to 93% in the vaccine-naïve 7- to 10-year-olds and 81% to 92% in 11- to 15-year-olds.
“In previously vaccinated children, GMT increase ranged between 55-fold and 205-fold compared with a 6-fold to a 27-fold increase in vaccine-naïve subjects,” Dr. Block noted. “Post-vaccination GMTs were significantly higher in previously vaccinated children.”
“A single dose of MenACWY-CRM administered at 7–15 years of age was well-tolerated with an acceptable safety profile, in both previously vaccinated and vaccine-naïve children,” Dr. Block concluded.