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 adolescents at age 11 or 12 years to protect them from meningococcal disease as older teens. The peak age for meningococcal disease is 16 through 21 years. Subsequent studies indicated that the protection provided by MenACWY wanes within 5 years following vaccination. For this reason, in 2010, ACIP recommended a MenACWY booster dose to provide continuing protection during the age of increased meningococcal incidence.