4CMenB vaccine did not reduce infection rates compared to placebo in MSM populationTrial shows 4CMenB vaccine does not prevent gonorrhea or syphilis

BACKGROUND: No vaccines are currently licensed for the prevention of infection. Observational studies suggest that the four-component meningococcal serogroup B vaccine (4CMenB) may reduce the risk of gonorrhea. METHODS: In this multicenter, double-blind, randomized, placebo-controlled trial, we assigned, in a 1:1 ratio, men who have sex with men (MSM) to receive two doses of 4CMenB or placebo. All the participants had recently received a diagnosis of infection or infectious syphilis and either tested negative for human immunodeficiency virus (HIV) and were receiving HIV preexposure prophylaxis or were living with HIV. Screening for sexually transmitted infections, including nucleic acid amplification testing of samples obtained from urogenital, anorectal, and oropharyngeal sites, was performed quarterly for 2 years. The primary outcome was a first infection after the receipt of vaccine or placebo in the per-protocol population (participants who received both 4CMenB or placebo doses, attended at least two scheduled follow-up visits after the second dose, and did not meet any exclusion criterion pertinent to the assessment of efficacy). RESULTS: From July 2021 through May 2023, a total of 654 participants underwent randomization, of whom 587 were included in the primary analysis. The incidence of infection was 48.1 events per 100 person-years (160 events among 296 participants) in the 4CMenB group and 47.8 events per 100 person-years (155 events among 291 participants) in the placebo group (incidence rate ratio, 1.01; 95% confidence interval [CI], 0.80 to 1.26; P = 0.97), for a vaccine efficacy of -0.5% (95% CI, -26.2 to 19.9). Vaccine efficacy was 5.5% (95% CI, -56.0 to 42.8) for symptomatic infection, -6.4% (95% CI, -47.5 to 23.2) for asymptomatic infection, and -20.0% (95% CI, -90.2 to 23.9), -1.2% (95% CI, -33.0 to 23.0), and 2.6% (95% CI, -27.7 to 25.7) for urogenital, anorectal, and oropharyngeal infection, respectively. Serious adverse events occurred in 4.7% of the participants in the 4CMenB group and in 2.8% of those in the placebo group. CONCLUSIONS: 4CMenB did not result in a lower incidence of infection than placebo among MSM who were at high risk for gonorrhea. (Funded by the Australian National Health and Medical Research Council and GSK; GoGoVax ClinicalTrials.gov number, NCT04415424.).