Meningococcal B Vaccine Elicits Bactericidal Responses Against Diverse Strains

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Headache and fatigue were the most common systemic events among both adolescents and young adults.
Headache and fatigue were the most common systemic events among both adolescents and young adults.

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.

 

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.

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