antibody and antibody avidity consistent with the induction of immune memory (Pichichero et al 2006). A UK study gave MCV4 to children 2 to 5 years old who had previ- ously received the monovalent meningococcal C conjugate vaccine. All 44 children developed SBA titers 8 to all four serogroups with a booster response observed to serogroup C (El Bashir et al 2006). In October, 2007 the FDA subse- quently licensed MCV4 for use in children aged 2–10 years (MMWR 2007). Another study compared vaccine doses of 1, 4, and 10 μg for each of the four polysaccharide serogroups conjugated to diphtheria toxoid that were given to infants at 2, 4, and 6 months of age. Presumed protective SBA levels /= 1:8 varied from 54% to 92% 1 month after the primary series depending upon vaccine serogroup and polysaccharide dose. A polysaccharide content of 10 μg was associated with more frequent local reactions but not with a corresponding increase in immunogenicity than lower doses of each serogroup (Rennels et al 2004). Consequently, there is no advantage to having a higher dose of the polysaccharide serogroups in the diphtheria toxoid conjugate vaccine. Guillain-Barré Syndrome (GBS) among MCV4 recipients In October 2005, reports suggested a possible association of GBS with MCV4, and the ACIP recommended that persons with a past history of GBS not be vaccinated with MCV4 unless they are at high risk for meningococcal disease (MMWR 2006). As of October 2007, there were 24 con- ﬁrmed reports of GBS after administration of MCV4 to the US Vaccine Adverse Event Reporting System (Clark 2007). However, no cases of GBS were reported among 11- to 19-year-olds within 6 weeks after more then 200,000 doses of MCV4 from the Vaccine Safety Datalink project (Clark 2007). The excess risk of GBS is currently estimated to be from 0.4 to 1.3 per million doses (Clark 2007). The beneﬁts of MCV4 are currently considered to signiﬁcantly outweigh the potential risks, except in patients with a prior history of GBS (see contraindications and precautions). Indications for use of MCV4 Table 2 lists the recommendations for the use of MCV4 made by the CDC Advisory Committee on Immunization Practices. It is routinely recommended for all US children aged 11–18 years, including those at additional risk. The vaccine is now recommended for use in at-risk children ages 2–10 years (MMWR 2007) and at-risk adults aged 19–55 years. Persons aged 2–55 years who continue to be at risk for meningococcal Therapeutics and Clinical Risk Management 2008:4(4) Tetravalent meningococcal conjugate vaccine for meningococcal disease Table 2 Recommendations for use of tetravalent (A, C,Y,W-135) meningococcal conjugate vaccine Population type Ages (years) Routine vaccination All persons aged 11–18 years 11–18 Persons at increased risk for meningococcal disease College freshmen living in dormitories 19–55 Military recruits 19–55 Microbiologists routinely exposed to isolates 19–55 of Neisseria meningitidis Persons with anatomic or functional asplenia or 2–55 terminal complement deﬁciencies Travelers to or residents of countries in 2–55 which N. meningitidis is hyperendemic or epidemic, especially sub-Saharan Africa during the dry season (December–June) or Saudi Arabia during the Hajj Persons infected with HIVa 2–55 aPersons with human immunodeﬁciency virus (HIV) are likely at increased risk of menin- gococcal disease,although not to the extent that they are at risk for invasive Streptococcus pneumoniae infection.The efﬁcacy of MCV4 among HIV-infected persons is unknown. Derived from Bilukha and Rosenstein (2005) with update from MMWR (2007). infection, despite having been vaccinated with MPSV4 3 or more years earlier, are also candidates for revaccination with MCV4 (Bilukha and Rosenstein 2005). The FDA has not approved the vaccine for use in children younger then 2 years or adults older then 55 years. Consequently MPSV4 could be substituted for adults older than 55 years. Contraindications and precautions to use of MCV4 Administration of MCV4 is contraindicated among persons known to have a severe allergic reaction to any component of the vaccine, including diphtheria toxoid or to natural latex rubber. MCV4 is an inactivated vaccine and may be given to immunosuppressed persons, but this may result in subopti- mal immune response. No data are available about its safety during pregnancy (Bilukha and Rosenstein 2005). A history of GBS is considered a precaution to administering MCV4, and MPSV4 is an acceptable short-term alternative providing protection for approximately 3–5 years (MMWR 2007). Cost effectiveness of MCV4 Cost effectiveness of meningococcal vaccination has been somewhat controversial, especially with the polysaccharide MPSV4 vaccine in developed countries where the vast majority of meningococcal cases are sporadic. One analysis estimated that vaccinating all US college freshmen living in dormitories with MPSV4 would cost US$0.6–$1.9 million per case averted and US$7–20 million per death averted 743