The clinical efficacy of Bexsero has not been evaluated through clinical trials.
Vaccine efficacy has been inferred by demonstrating the induction of serum bactericidal antibody responses to each of the vaccine antigens:
- Serum bactericidal antibody responses to each of the vaccine antigens NadA, fHbp, NHBA and PorA P1.4 were evaluated using a set of four meningococcal group B reference strains.
- Bactericidal antibodies against these strains were measured by the Serum Bactericidal Assay using human serum as the source of complement (hSBA).
- Most of the primary immunogenicity studies were conducted as randomized, controlled, multicenter, clinical trials. Immunogenicity was evaluated in infants, children, adolescents and adults.
- In summary, the majority of infants, 2 months to 6 months of age achieved titers expected to be protective after priming with Bexsero for each of the vaccine antigens. 1
- Similarly, seroresponse rates and hSBA GMTs were high and similar after the two-dose series in infants 6-8 months of age and children, 13-15 and 24-26 months of age against each of the vaccine antigens. 1
- Robust immune responses were seen against all four strains in infants after the primary series and in children aged 12 months after a booster dose. 4
- In adolescents (11–17 years of age), each of the 4 antigenic components in Bexsero gives a robust response. 1
- Following Bexsero vaccination, a high percentage of subjects in the adolescent study were seropositive and achieved 4-fold increases in hSBA titers independent of pre-vaccination status. 1
- Only 2 doses of Bexsero are required, ≥1 month apart (for individuals ≥11 years of age).* 1
- In children and adolescents with complement deficiencies, asplenia or splenic dysfunction a robust immune response was shown. 1
- In adults, similar data were obtained after two doses of Bexsero with a two month interval between doses. 1
*A booster dose should be considered in individuals at continued risk of exposure to meningococcal disease, based on official recommendations. 1
Estimation of the effectiveness of Bexsero vaccination requires knowledge of MenB strain coverage in addition to immunogenicity. 3
The Meningococcal Antigen Typing System (MATS) evaluates the degree to which circulating MenB strains express NadA, NHBA, PorA and fHbp, thus predicting Bexsero coverage. 3
MATS analysis of a panel of strains can be done in weeks, rather than the months or years of work that would be required to test each strain individually and provides vaccine coverage estimates from large panels of bacterial strains. 4
MATS evaluation from 13 countries around the world estimated that 66 to 91% would have been covered by Bexsero 2
Bexsero is not expected to provide protection against all circulating meningococcal serogroup B strains and not all vaccine recipients will be protected from the disease. 1