Bexsero

The immunogenicity of Bexsero following 2 doses was evaluated in individuals aged 11–24 years. Serum bactericidal antibodies were measured with hSBA assays using 3 strains selected to measure responses to 1 of 3 vaccine antigens, either fHbp, NadA, or PorA P1.4, prevalent among strains in the US. A suitable strain for assessing bactericidal activity of NHBA-specific antibodies was not available.

Studies evaluated the proportion of subjects who achieved a 4-fold or greater increase in hSBA titer for each of the 3 strains, and the proportion of subjects with a titer greater than or equal to the lower limit of quantitation (LLOQ) of the assay for all 3 strains (composite response). The LLOQ was defined as the lowest amount of the antibody in a sample that can be reliably quantified. Available data showed that baseline antibody titers across populations vary.

In the Canada/Australia clinical trial, adolescents aged 11–17 years received 2 doses of Bexsero 1 month apart.

• The hSBA responses 1 month after the second dose are shown below:
  
  • Strain:
    
    • H44/76 (fHbp):  98% (95% CI, 95–99)
    • 5/99 (NadA):  99% (95% CI, 98–100)
    • NZ98/254 (PorA P1.4):  39% (95% CI, 33–44)
  • Composite hSBA Response:
    
    • Time Point (Baseline [pre-vaccination]):  0%
    • Time Point (1 Month Post Dose 2):  63% (95% CI, 57–68)

In the randomized, controlled clinical trial conducted in the UK among university students aged 18–24 years, hSBA responses in a subset of participants who received Bexsero were measured 1 month and 11 months after the second dose.

• The hSBA responses are shown below:
  • Strain:
    • H44/76 (fHbp):  78% (95% CI, 71–85)
    • 5/99 (NadA):  94% (95% CI, 89–97)
    • NZ98/254 (PorA P1.4):  67% (95% CI, 58–74)
  • Composite hSBA Response:
    
    • Time Point (Baseline [pre-vaccination]):  24% (95% CI, 18–30)
    • Time Point (1 Month Post Dose 2):  88% (95% CI, 82–93)
    • Time Point (11 Months Post Dose 2):  66% (95% CI, 58–72)