Meningococcal B Vaccine Immunogenicity in Children With Defects in Complement and Splenic Function.

Area of Science:

• Immunology
• Vaccinology
• Pediatrics

Background:

• The quadrivalent meningococcal group B vaccine (4CMenB) is recommended for at-risk children, including those with complement deficiencies, asplenia, or splenic dysfunction.
• Limited data exist on the immunogenicity of 4CMenB in these specific pediatric populations.

Purpose of the Study:

• To evaluate the immunogenicity of the 4CMenB vaccine in children with complement deficiencies, asplenia, or splenic dysfunction.
• To compare vaccine responses in these at-risk groups with healthy children.

Main Methods:

• A study involving 239 children aged 2-17 years, including those with complement deficiencies (n=40), asplenia/splenic dysfunction (n=112), and healthy controls (n=87).
• Participants received two doses of 4CMenB, and serum bactericidal activity (SBA) was measured using exogenous and endogenous complement against four Neisseria meningitidis serogroup B strains.
• SBA was assessed at baseline and one month post-vaccination.

Main Results:

• After vaccination, high proportions of participants with asplenia/splenic dysfunction and healthy controls achieved serum bactericidal activity (SBA) titers ≥1:5 against all tested strains using exogenous complement.
• Complement-deficient children showed slightly lower SBA titers compared to controls, particularly those with terminal complement deficiencies or on eculizumab therapy.
• Strain-specific bactericidal activity with endogenous complement was limited in participants with severe complement deficiencies.

Conclusions:

• The 4CMenB vaccine demonstrates comparable immunogenicity in healthy children and those with asplenia or splenic dysfunction.
• A trend towards lower SBA responses was noted in some complement-deficient children, highlighting the need for continued surveillance for vaccine effectiveness in these vulnerable groups.