Meningococcal B vaccine (4CMenB) programs have shown high vaccine protection against meningococcal B disease. Real-world evidence also suggests meningococcal B vaccines with OMV-based antigens offer moderate protection against gonorrhoea. Gonorrhoea has become a major public health problem, because of rapid development of antimicrobial resistance. Proteins targeted by 4CMenB are present in both N. meningitidis and Neisseria gonorrhoeae. Very high genomic similarities exist between the 4CMenB vaccine antigens and N. gonorrhoeae protein sequences. The high sequence identity for NHBA proteins in N. meningitidis and N. gonorrhoeae suggests a protective effect induced by 4CMenB in addition to the protection provided by the OMV vaccine.
Evaluation of the 4CMenB adolescent program in South Australia was undertaken at three years post introduction of an infant and adolescent program. Vaccine impact on gonorrhoea was assessed using a negative binomial regression model. Vaccine effectiveness (VE) was estimated using screening and case-control methods. Chlamydia controls were used to estimate VE to control potential confounding effects such as high-risk sexual behaviour associated with sexually transmitted infections.
There was an estimated 30.0% reduction (aIRR=0.700; 95%CI 0.429-1.141) in the incidence of gonorrhoea in adolescents aged 15-17 years at three years. Vaccine effectiveness against gonorrhoea in adolescents following two doses was 33.2% (95%CI 15.9%-47.0%). Lower VE estimates were demonstrated after 36 months post-vaccination (23.2% (95%CI 0-47.5%) >36 months post-vaccination compared to 34.9% (95%CI 15.0%-50.1%) within 6-36 months). Higher VE estimates were found after excluding patients with repeat gonorrhoea infections (37.3%, 95%CI 19.8%-51.0%). For gonorrhoea cases co-infected with chlamydia VE was maintained (44.7% (95%CI 17.1%-63.1%).
In this is first 4CMenB vaccine ongoing program for adolescents globally, there was evidence of sustained moderate vaccine protection against gonorrhoea with waning of vaccine effectiveness three years post-vaccination in adolescents and young adults. A booster dose may need to be further evaluated and considered in adolescents due to waning protection against gonorrhoea demonstrated after 36 months post-vaccination.