Why does ACIP recommend a routine booster dose of MenACWY for adolescents at age 16 years?

In 2005, ACIP recommended routine MenACWY vaccination for all preteens at age 11 or 12 years to protect them from meningococcal disease when its incidence rises in the late teens and early 20s. Subsequent studies indicated that the protection provided by MenACWY waned within 5 years following vaccination. For this reason, in 2010, ACIP recommended a MenACWY booster dose at age 16 to provide continuing protection during the age of increased meningococcal incidence.