What is the recommended dosing schedule for Haemophilus influenzae type b (Hib) and meningococcal vaccines in patients undergoing splenectomy?

Vaccination Recommendations for Haemophilus influenzae type b (Hib) and Meningococcal Vaccines in Splenectomy Patients

For patients undergoing splenectomy, Hib vaccination requires a single dose, while meningococcal vaccination requires a two-dose primary series of MenACWY followed by boosters every 5 years, plus a MenB series with boosters every 2-3 years for those aged ≥10 years. 1

Haemophilus influenzae type b (Hib) Vaccination

Timing of Vaccination

• Ideally, Hib vaccine should be administered at least 2 weeks before elective splenectomy 1, 2
• If pre-splenectomy vaccination is not feasible, immunization should be given after splenectomy, as patients can still mount a protective antibody response 1

Dosing Schedule

• For adults (≥15 months) undergoing elective splenectomy who are unimmunized: 1 dose prior to procedure 1
• For asplenic patients aged >59 months and adults who are unimmunized: 1 single dose 1
• The pediatric Hib vaccine is considered optional for adults due to limited efficacy data, though studies suggest good immunogenicity in immunocompromised patients 1, 3

Special Considerations

• Long-term antibody response may wane in some patients, with some studies showing declining antibody levels 2-3 years after vaccination 3
• Immunization is particularly important as asplenic patients are at increased risk for invasive disease from encapsulated organisms including H. influenzae 4

Meningococcal Vaccination

MenACWY (Serogroups A, C, W, and Y)

• Primary vaccination for asplenic patients aged ≥10 years: 2 doses of MenACWY given ≥8 weeks apart 1
• Booster doses: Single dose at 5 years after primary vaccination and every 5 years thereafter if the person remains at increased risk 1
• The vaccine should ideally be administered at least 2 weeks before elective splenectomy 1

MenB (Serogroup B)

• For asplenic patients aged ≥10 years: 1
  • MenB-FHbp: 3-dose series at 0,1-2, and 6 months, OR
  • MenB-4C: 2-dose series given ≥1 month apart
• Booster doses: Single dose at 1 year after completion of primary vaccination and every 2-3 years thereafter 1
• Note: MenB-FHbp and MenB-4C are not interchangeable 1

Age-Specific Recommendations

• For children aged 2-9 years with asplenia: 1
  • MenACWY only (2 doses ≥8 weeks apart)
  • Boosters: Single dose at 3 years after vaccination and every 5 years thereafter for children <7 years
  • Boosters: Single dose at 5 years and every 5 years thereafter for children ≥7 years
  • No recommendations for MenB vaccines in this age group
• For infants aged 2-23 months with asplenia: MenACWY-CRM only with specific dosing schedules based on age at first dose 1

Clinical Pearls and Pitfalls

• Timing is critical: Ideally, vaccinations should be given at least 2 weeks before elective splenectomy to ensure optimal immune response 1, 2
• Don't delay post-splenectomy: If pre-operative vaccination isn't possible, proceed with vaccination after surgery, as patients can still develop protective immunity 1
• Vaccine interchangeability: While the same MenB product must be used for all doses, MenACWY vaccines are interchangeable 1
• Vaccination coverage gaps: Studies show suboptimal vaccination coverage in splenectomized patients, with only 18.7% receiving Hib vaccine in some populations 5
• Breakthrough infections: Vaccination according to guidelines could prevent approximately 28% of post-splenectomy invasive bacterial infections 5
• Consider anatomic factors: Near-total splenectomy may provide better immunological basis for both natural and vaccine-induced protection compared to complete splenectomy 6

Remember that these vaccinations are crucial preventive measures against potentially life-threatening infections in asplenic patients, who are at significantly increased risk for overwhelming post-splenectomy infections due to encapsulated organisms 4.