Are Menectra and Menomune the Same Vaccine?
No, Menectra and Menomune are fundamentally different vaccines with distinct mechanisms of action, though both protect against the same four meningococcal serogroups (A, C, Y, and W-135).
Key Differences
Vaccine Type and Composition
Menomune (MPSV4) is a quadrivalent meningococcal polysaccharide vaccine licensed in 1981, containing 50 μg of each purified capsular polysaccharide from serogroups A, C, Y, and W, administered subcutaneously 1
Menactra (MCV4/MenACWY-D) is a quadrivalent meningococcal conjugate vaccine licensed in 2005, containing 4 μg of each capsular polysaccharide conjugated to approximately 48 μg of diphtheria toxoid, administered intramuscularly 1, 2
Immunologic Mechanism
The critical distinction lies in how these vaccines generate immunity:
Polysaccharide vaccines (Menomune) induce a T-lymphocyte–independent immune response, resulting in limited immunologic memory and poor responses in young children 1
Conjugate vaccines (Menactra) produce a T-lymphocyte–dependent immune response through conjugation to a protein carrier, resulting in improved primary responses (especially in infants), stronger anamnestic responses, and immunologic memory 1
Clinical Implications
Duration of protection: Menomune does not confer long-lasting immunity and does not substantially reduce nasopharyngeal carriage of N. meningitidis, failing to interrupt transmission or elicit herd immunity 1. In contrast, conjugate vaccines like Menactra provide longer-lasting protection with immunologic memory 1
Age-related efficacy: The serogroup C polysaccharide in Menomune is poorly immunogenic in children under 2 years of age 1. Menactra demonstrates superior immunogenicity across age groups, including young children 1
Hyporesponsiveness risk: Multiple doses of polysaccharide vaccines may cause immunologic hyporesponsiveness to serogroups A and C, though clinical implications remain unclear 1. This phenomenon does not occur with conjugate vaccines 1
Current Recommendations
Menactra is now the preferred vaccine for routine immunization in persons aged 9 months through 55 years 1, 2. ACIP recommends that persons previously vaccinated with either Menactra or Menomune who remain at prolonged increased risk should be revaccinated with Menactra (the conjugate vaccine) 1
Menomune may still be used when Menactra is contraindicated (such as in pregnancy or breastfeeding if indicated) or unavailable, but it represents older vaccine technology with inferior immunologic properties 1
The shift from polysaccharide to conjugate meningococcal vaccines mirrors the successful transitions seen with Haemophilus influenzae type b and pneumococcal vaccines, where conjugate technology dramatically improved disease prevention 1