According to the results from 2 phase 3 studies (ClinicalTrials.gov identifier: NCT01830855 and NCT01352845) published in The New England Journal of Medicine, a licensed meningococcal B vaccine targeting factor H-binding protein (MenB-FHbp) elicited immune responses against diverse strains of group B meningococcus with rates of adverse events that were comparable in the treatment and control groups.

A total of 3596 adolescents between the ages of 10 and 18 years were randomly assigned to receive MenB-FHbp or hepatitis A virus vaccine and saline, and 3304 young adults between the ages of 18 to 25 years were randomly assigned to receive MenB-FHbp or saline. Vaccines or saline were given at baseline, at 2 months, and at 6 months. 

Serum bactericidal assays including human complements (hSBAs) were used to evaluate the immunogenicity of the vaccine against 14 meningococcal B test strains. An increase in hSBA titer by a factor of 4 was considered an acceptable correlate of protection for the meningococcal strains.

After the second MenB-FHbp dose, the proportion of adolescents with an increase in hSBA titer by a factor of 4 ranged from 56.0% to 85.3% depending on the strain. This increased to 78.8% to 90.2% after the third dose. The proportion of adolescents who had a 4-factor increase in hSBA titer for all 4 primary meningococcal strains was 53.7% and 82.7% after dose 2 and 3, respectively.

Among young adults, the proportion of participants with a 4-factor increase in hSBA titer ranged from 54.6% to 85.6% after dose 2 and 78.9% to 89.7% after dose 3. A total of 63.3% and 84.5% of young adults had a 4-factor increase in hSBA titers for all 4 primary meningococcal strains following dose 2 and 3, respectively.

Responses to the 4 primary meningococcal strains predicted the responses for the 10 remaining diverse meningococcal B strains positively.

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Injection site pain was more common in the MenB-FHbp group compared with the hepatitis A vaccine or saline groups. Overall, adverse events occurred at similar rates between groups, with most adverse events categorized as mild or moderate. No vaccine-related serious adverse events were reported.

The study authors concluded that, “broadly protective hSBA responses were observed in both of these phase 3 trials after three doses of MenB-FHbp.” They highlighted that the vaccine elicited an immune response “against an antigenically and epidemiologically diverse panel of primary test strains. These strains were representative of disease-causing meningococcal B isolates expressing factor H-binding proteins that are different from vaccine antigens.”

Disclosure: Both studies were funded by Pfizer.

Reference

Ostergaard L, Vesikari T, Absalon J, et al; for the B1971009 and B1971016 Trial Investigators. A bivalent meningococcal B vaccine in adolescents and young adults. N Engl J Med. 2017;377:2349-2362.