Meningococcal Vaccines

Introduction to Meningococcal Vaccines

Meningococcal vaccines are designed to prevent infections caused by Neisseria meningitidis, a bacterium responsible for meningococcal disease. This disease can manifest as meningitis (inflammation of the meninges surrounding the brain and spinal cord) or septicemia (bloodstream infection), both of which can be life-threatening.

Key Points:

  • N. meningitidis is classified into 12 serogroups, with A, B, C, W, X, and Y being the main causes of disease worldwide.
  • Meningococcal vaccines target specific serogroups and can be either polysaccharide or conjugate vaccines.
  • These vaccines are crucial for preventing invasive meningococcal disease, which has a high mortality rate and can cause severe long-term sequelae in survivors.
  • The first meningococcal vaccine was developed in the 1970s, with significant advancements made since then.

Types of Meningococcal Vaccines

There are several types of meningococcal vaccines available, targeting different serogroups:

1. Quadrivalent Conjugate Vaccines (MenACWY)

  • Protect against serogroups A, C, W, and Y
  • Available brands: Menactra, Menveo, and MenQuadfi
  • Conjugate vaccines link the polysaccharide antigen to a protein carrier, enhancing immune response

2. Serogroup B Vaccines (MenB)

  • Protect against serogroup B
  • Available brands: Bexsero (MenB-4C) and Trumenba (MenB-FHbp)
  • Use protein antigens rather than polysaccharides

3. Polysaccharide Vaccine (MPSV4)

  • Protects against serogroups A, C, W, and Y
  • Brand: Menomune (no longer available in the US as of 2017)
  • Less effective than conjugate vaccines, especially in young children

4. Combination Vaccines

  • MenHibrix: Combined Hib and meningococcal C and Y vaccine (no longer available in the US)
  • Research ongoing for pentavalent (ACWYX) and combination vaccines with other pathogens

Vaccine Efficacy

The efficacy of meningococcal vaccines varies depending on the type of vaccine and the serogroup targeted.

Quadrivalent Conjugate Vaccines (MenACWY):

  • Short-term efficacy: 80-85% for all four serogroups
  • Long-term efficacy: Declines over time, particularly for serogroup A
  • Booster doses recommended to maintain protection

Serogroup B Vaccines (MenB):

  • Bexsero: 63-94% efficacy against MenB strains in the UK
  • Trumenba: 81-84% efficacy against diverse MenB strains
  • Efficacy may vary due to strain diversity and regional differences

Polysaccharide Vaccine (MPSV4):

  • 85-100% efficacy in adults
  • Less effective in young children and does not induce long-lasting immunity
  • Does not reduce nasopharyngeal carriage

Herd Immunity:

Conjugate vaccines have shown to reduce nasopharyngeal carriage, leading to herd immunity effects in populations with high vaccination coverage.

Vaccination Schedule

The Advisory Committee on Immunization Practices (ACIP) recommends the following meningococcal vaccination schedules:

Routine Vaccination (MenACWY):

  • First dose: 11-12 years of age
  • Booster dose: 16 years of age

MenB Vaccination:

  • Recommended for individuals 16-23 years old (preferably 16-18) based on shared clinical decision-making
  • Two-dose series of Bexsero or three-dose series of Trumenba

High-Risk Groups:

  • Individuals with certain medical conditions (e.g., asplenia, complement deficiencies)
  • Laboratory personnel routinely exposed to N. meningitidis
  • People in outbreaks or high-risk settings (e.g., military recruits)
  • Travelers to endemic areas

Vaccination During Outbreaks:

Specific recommendations are made by public health authorities based on the serogroup causing the outbreak and the affected population.

Side Effects and Safety

Meningococcal vaccines are generally safe, but like all vaccines, they can cause side effects.

Common Side Effects:

  • Pain, redness, or swelling at the injection site
  • Fever
  • Headache
  • Fatigue
  • Muscle or joint pain

Rare Side Effects:

  • Severe allergic reactions (anaphylaxis): Estimated at 0.3 cases per million doses for MenACWY
  • Guillain-Barré Syndrome (GBS): A possible but unproven association with meningococcal vaccines

Safety Monitoring:

Continuous monitoring through various systems, including:

  • Vaccine Adverse Event Reporting System (VAERS)
  • Vaccine Safety Datalink (VSD)
  • Post-licensure studies

Contraindications and Precautions:

  • Severe allergic reaction to a previous dose or vaccine component
  • Moderate or severe acute illness (temporary precaution)
  • Pregnancy: MenACWY may be used if indicated, limited data on MenB in pregnancy

Public Health Impact

Meningococcal vaccination programs have significantly reduced the incidence of invasive meningococcal disease in many countries.

Impact on Disease Incidence:

  • UK: 99% reduction in MenC cases following introduction of MenC vaccine in 1999
  • US: 80% decline in incidence of serogroup C, Y, and W disease from 1996 to 2013
  • Africa: Successful elimination of MenA epidemics in the "meningitis belt" following mass vaccination campaigns

Herd Immunity Effects:

  • Significant reductions in disease among unvaccinated age groups observed in countries with high vaccination coverage
  • Reduction in nasopharyngeal carriage, particularly with conjugate vaccines

Global Impact:

WHO initiatives like the Meningitis Vaccine Project have led to widespread use of MenA conjugate vaccine in Africa, dramatically reducing MenA epidemics.

Challenges:

  • Serogroup replacement: Potential increase in non-vaccine serogroups
  • Vaccine accessibility in low- and middle-income countries
  • Maintaining high vaccination coverage in adolescents and young adults
  • Addressing the diversity of MenB strains

Future Directions:

  • Development of broader coverage vaccines, including pentavalent vaccines
  • Improved strategies for outbreak control and prevention
  • Ongoing surveillance to monitor serogroup distribution and vaccine impact


Meningococcal Vaccines
  1. Q: What bacterium causes meningococcal disease? A: Neisseria meningitidis
  2. Q: How many main serogroups of N. meningitidis are responsible for most meningococcal disease? A: 5 (A, B, C, W, and Y)
  3. Q: What type of meningococcal vaccine protects against serogroups A, C, W, and Y? A: Quadrivalent conjugate vaccine (MenACWY)
  4. Q: At what age is the first dose of MenACWY vaccine typically recommended in the US? A: 11-12 years old
  5. Q: How many doses of MenACWY vaccine are recommended for adolescents in the US? A: 2 doses (initial dose at 11-12 years, booster at 16 years)
  6. Q: What type of meningococcal vaccine specifically targets serogroup B? A: MenB vaccine
  7. Q: How is the meningococcal conjugate vaccine typically administered? A: Intramuscular injection
  8. Q: What is the minimum age for receiving the MenACWY vaccine? A: 2 months (for high-risk infants)
  9. Q: Which serogroup of N. meningitidis is most common in the "meningitis belt" of sub-Saharan Africa? A: Serogroup A
  10. Q: What is the name of the meningococcal vaccine specifically developed for use in Africa? A: MenAfriVac
  11. Q: How long does protection from a single dose of MenACWY vaccine typically last? A: 3-5 years
  12. Q: What percentage of people carry N. meningitidis in their nasopharynx without symptoms? A: 10-20%
  13. Q: What is the typical incubation period for meningococcal disease? A: 3-4 days
  14. Q: What is the case fatality rate for meningococcal meningitis even with appropriate treatment? A: 8-15%
  15. Q: Which group is at highest risk for meningococcal disease? A: Infants under 1 year old
  16. Q: What is the storage temperature requirement for most meningococcal vaccines? A: 2-8°C (35-46°F)
  17. Q: How quickly can meningococcal disease progress from initial symptoms to death? A: 24-48 hours
  18. Q: What is the most common presentation of invasive meningococcal disease? A: Meningitis
  19. Q: What is the second most common presentation of invasive meningococcal disease? A: Septicemia
  20. Q: In which year was the first meningococcal conjugate vaccine licensed? A: 1999 (in the UK)
  21. Q: What is the typical dosage of MenACWY vaccine for individuals 11 years and older? A: 0.5 mL
  22. Q: How many doses of MenB vaccine are typically recommended for healthy adolescents? A: 2 or 3 doses (depending on the specific vaccine)
  23. Q: What is the name of the protein used to conjugate the polysaccharides in some meningococcal vaccines? A: CRM197 (modified diphtheria toxin)
  24. Q: Which continent has the highest incidence of meningococcal disease? A: Africa
  25. Q: What is the term for the characteristic skin rash associated with meningococcal septicemia? A: Purpura fulminans
  26. Q: What percentage of survivors of meningococcal disease experience long-term sequelae? A: 10-20%
  27. Q: Which group is recommended to receive the MenB vaccine routinely in the US? A: Individuals at increased risk (e.g., during outbreaks, certain medical conditions)
  28. Q: What is the minimum interval between doses of MenB vaccine? A: 1 month
  29. Q: In which season does meningococcal disease most commonly occur? A: Winter and early spring
  30. Q: What is the name of the outer membrane vesicle (OMV) component used in some MenB vaccines? A: PorA P1.4


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