Background: Multiple epidemiologic studies have demonstrated that immunization with the four component meningococcal serogroup B (4CMenB) vaccine is associated with reduced gonococcal infections. However, multiple clinical trials conducted in study participants with high risk of gonococcal infections have failed to demonstrate 4CMenB administration provided a statistically significant reduction in gonococcal infection. Whether 4CMenB protects against gonococcal infection in individuals with low risk for infection remains unknown
Aims/Methods: A controlled human infection model of gonococcal urethritis was utilized in a randomized, blinded phase II study testing whether immunization with 4CMenB prevents urethral gonococcal infection. Healthy volunteers assigned male sex at birth who met all inclusion criteriawere randomized to receive either 2 doses of 4CMenB or control (Influenza and Tetanus/Diptheria) vaccines followed by urethral inoculation with N. gonorrhoeae strain FA1090. After inoculation, participants were monitored for the development of gonococcal infection (defined as a positive urine nucleic acid test for N. gonorrhoeae or positive culture for N. gonorrhoeae of urine or urethral swab on the day of treatment) and of urethritis for up to 10 days. The primary objective was to determine whether immunization with 4CMenB was associated with reduced incidence of gonococcal infection after inoculation.
Results: 85 individuals consented for screening and 65 individuals were found to be eligible, were enrolled and randomized in the study. The median age of the 65 enrollees was 28 (IQR 7 years) and 19 (29%) individuals had a history of N. gonorrhoeae, Chlamydia trachomatis, or syphilis. Fifty-one individuals received the assigned immunizations and underwent successful urethral inoculation with N. gonorrhoeae. Of all inoculated individuals, twenty-eight (55%) developed gonococcal infection.
Conclusions: In this study, the majority of the study population had low risk for gonococcal infection, it is the first trial of 4CMenB efficacy to include individuals in this risk category. The attack rate for gonococcal infection after urethral inoculation in this study was lower than in prior controlled human infection studies utilizing FA1090. Data determining whether 4CMenB immunization was associated with this reduced attack rate and serologic findings in the study participants will be available at the time of the conference.