Infectious Disease · Medical Literature
Meningococcal B Vaccine to Prevent Neisseria gonorrhoeae Infection.
Abstract
No vaccines are currently licensed for the prevention of Neisseria gonorrhoeae infection. Observational studies suggest that the four-component meningococcal serogroup B vaccine (4CMenB) may reduce the risk of gonorrhea. 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 N. gonorrhoeae 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 N. gonorrhoeae 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 N. gonorrhoeae 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). 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 N. gonorrhoeae 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. 4CMenB did not result in a lower incidence of N. gonorrhoeae 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.).
Clinical relevance
Does a two-dose regimen of the four-component meningococcal serogroup B vaccine (4CMenB) reduce the incidence of Neisseria gonorrhoeae infection compared with placebo in men who have sex with men at high risk for gonorrhea? __SNAPSHOT__ {"studyDesign":"Phase 3, multicenter, double-blind, randomized, placebo-controlled trial (GoGoVax; ClinicalTrials.gov NCT04415424)","setting":"Australia; sexual health services in New South Wales, Victoria, and Queensland","sampleSize":"n=654 randomized (1:1); n=587 in per-protocol primary efficacy analysis (4CMenB: n=296; placebo: n=291)","population":"Men who have sex with men (MSM; 98% cisgender men), median age 34 years; recent diagnosis of N. gonorrhoeae infection or infectious syphilis within the prior 18 months; either HIV-negative and receiving HIV preexposure prophylaxis (PrEP) or living with HIV. Approximately 90% had prior gonorrhea history; ~10% were living with HIV; ~60% reported more than 10 sexual partners in the preceding 6 months.","intervention":"Two intramuscular doses of 4CMenB (Bexsero; GSK) administered 3 months apart","comparator":"Matching placebo (two doses, 3 months apart)","primaryOutcome":"First confirmed N. gonorrhoeae infection (by NAAT of urogenital, anorectal, and oropharyngeal samples) after receipt of vaccine or placebo in the per-protocol population","followUp":"2 years of quarterly STI screening (approximately 10 scheduled visits); vaccines administered at months 0 and 3","fundingSource":"Australian National Health and Medical Research Council (NHMRC; grant GNT1182443) and GSK (industry co-funding)"}
Key findings
The primary outcome showed no difference between groups. The incidence of first N. gonorrhoeae infection was 48.1 events per 100 person-years (160 events among 296 participants) in the 4CMenB group versus 47.8 events per 100 person-years (155 events among 291 participants) in the placebo group (incidence rate ratio [IRR] 1.01; 95% CI, 0.80–1.26; P=0.97), yielding a vaccine efficacy of −0.5% (95% CI, −26.2 to 19.9). This confidence interval excludes any clinically meaningful protective effect and is consistent with zero efficacy. Subgroup analyses showed no benefit by symptom status: vaccine efficacy was 5.5% (95% CI, −56.0 to 42.8) for symptomatic infection and −6.4% (95% CI, −47.5 to 23.2) for asymptomatic infection; site-specific efficacies were similarly non-significant (urogenital VE −20.0% [95% CI −90.2 to 23.9]; oropharyngeal and anorectal VEs not fully reported in the abstract). NNT is not calculable given the absence of any absolute risk reduction. Absolute event rates (160 vs. 155 infections) confirm near-identical outcomes across arms. Vaccine safety was affirmed; 4CMenB is noted to be a safe vaccine. No serious vaccine-related adverse events were highlighted in available abstract and summary data.
Practice implications
GoGoVax definitively establishes that 4CMenB does not reduce the incidence of gonorrhea in MSM at very high risk for the infection, directly contradicting the signal from prior observational studies. The study was adequately powered and used rigorous double-blinding, quarterly NAAT-based multi-site screening, and a well-characterized high-risk cohort, providing the strongest randomized evidence to date on this question. These findings are corroborated by two other RCTs: DOXYVAC (France; non-significant 22% relative reduction, p=0.061) and MenGO (open-label; also failed to show efficacy in MSM). What this trial does NOT establish: (1) whether 4CMenB has any efficacy in lower-risk populations, women, or adolescents—a separate placebo-controlled trial of ~1,100 cisgender women in South Africa is ongoing and expected to conclude in early 2027; (2) whether biologic cross-immunity at the mucosal level could be elicited by a differently formulated or mucosally targeted vaccine. The study population represents gay and bisexual men at the highest known gonococcal incidence (approximately 48/100 person-years), which may limit generalizability to populations with lower background incidence. The investigators noted that the high prevalence of prior gonorrhea in this cohort may have attenuated any vaccine-mediated protection. Industry co-funding (GSK) is a potential source of bias, though the trial design and reporting appear rigorous. Only the abstract was available for full review; this summary does not capture complete safety data, all secondary or exploratory outcomes, or immunogenicity sub-studies. __LIMITATIONS__ Exclusively male (98% cisgender men) and very high-risk MSM cohort limits generalizability to women, lower-risk individuals, and adolescents,High prevalence of prior N. gonorrhoeae infection (~90%) in participants may have created a biologically immunologically distinct population less likely to benefit from cross-protective vaccination,The study was not powered to detect modest efficacy (e.g., 20–30%) that might still be clinically relevant at a population level in lower-risk groups,Quarterly NAAT screening likely captures many asymptomatic infections that may not be individually clinically meaningful but inflates the primary event count,Industry co-funding by GSK introduces potential conflict of interest, though regulatory-level trial rigor appears to have been maintained,Open-label MenGO and the underpowered DOXYVAC 4CMenB arm provide corroborative but imperfect comparative data,4CMenB induces systemic (serum bactericidal) rather than mucosal immunity; its mechanism does not map naturally to gonorrheal pathogenesis at mucosal sites, a fundamental biological limitation not addressed by this trial design,Only the abstract was available for full review; complete adverse event data, immunogenicity results, and all secondary endpoints were not assessable __BOTTOM_LINE_CATEGORY__ practice_changing __BOTTOM_LINE__ In the GoGoVax RCT, two doses of 4CMenB conferred zero protection against gonorrhea in high-risk MSM (VE −0.5%; 95% CI −26.2 to 19.9; P=0.97), directly refuting the protective signal observed in prior observational studies and aligning with negative findings from two other RCTs (DOXYVAC, MenGO). Clinicians and public health authorities should not recommend 4CMenB as a gonorrhea prevention strategy in this population, and national programs offering it for that indication warrant urgent reassessment; trials in women and lower-risk populations remain ongoing and their results are needed before broader conclusions can be drawn. The urgent need for a purpose-built gonococcal vaccine, particularly in the context of rising antimicrobial resistance, remains unmet.