Meningococcal B Vaccine Not Effective Against Gonorrhea, RCT Finds

A large-scale randomized control trial (RCT) has found that the meningococcal B vaccine (4CMenB) does not prevent the acquisition of gonorrhea. This finding contradicts previous evidence from observational studies that had suggested an association.

"Gonorrhea incidence was approximately 48% per year across both groups, indicating no preventive effect from the vaccine."

GoGoVax Trial Details Unveiled

The definitive results were presented by Professor Kate Seib from Griffith University at the Conference on Retroviruses and Opportunistic Infections in Denver, Colorado. The study, a collaboration between Griffith University's Institute for Biomedicine and Glycomics and the Kirby Institute at UNSW Sydney, focused on gay and bisexual men. This population was specifically identified due to its particularly high risk of gonorrhea, a public health concern amplified by rising antibiotic-resistant strains.

The 'GoGoVax' trial was a double-blind, randomized, placebo-controlled study involving 587 gay and bisexual men. Participants received either the meningococcal vaccine or a saline placebo. The high incidence rate of gonorrhea, approximately 48% per year, was observed equally across both vaccine and placebo groups. This outcome indicates a clear lack of preventive effect from the 4CMenB vaccine, aligning with findings from the smaller DOXYVAC open-label trial.

Implications for Gonorrhea Prevention Strategies

Professor Andrew Grulich from the Kirby Institute highlighted the potential impact of an effective gonorrhea vaccine. "An effective gonorrhea vaccine would significantly change prevention strategies," he noted. However, the GoGoVax results confirm that the 4CMenB vaccine, while approved in Australia since 2013 and remaining safe and effective for preventing meningococcal disease, does not offer protection against gonorrhea.

Individuals who received the 4CMenB vaccine with the expectation of gonorrhea prevention are advised to consider other prevention methods, such as condoms and regular testing.

This advice, also from Professor Grulich, underscores the ongoing need for established prevention methods.

Targeted Population and Generalizability

The RCT specifically included gay and bisexual men with a recent history of gonorrhea or syphilis. This selection criterion was chosen because these groups were more likely to acquire gonorrhea during the study period.

Researchers acknowledge that the high rates of prior gonorrhea in this specific study population might affect the generalizability of the findings to other populations. Nevertheless, these results are considered an important and crucial finding for high-risk gay and bisexual men.

RCTs: The Gold Standard in Medical Research

The GoGoVax RCT was initiated following several observational studies that had suggested an association between the meningococcal B vaccine and reduced gonorrhea incidence. Some countries currently offer the vaccine to gay and bisexual men at high risk for gonorrhea based on these earlier data.

Observational studies, by their nature, can be influenced by confounding factors. For example, some case-control studies compared 4CMenB vaccination rates in people with gonorrhea to those with chlamydia, noting lower 4CMenB vaccination rates in gonorrhea cases. However, various other factors could have explained these observed differences, not necessarily a direct preventive effect of the vaccine.

Randomized Controlled Trials (RCTs) are widely regarded as the standard in medical research because proper randomization effectively removes potential confounding factors. Professor Grulich confirmed that good-quality randomization was achieved in GoGoVax, ensuring that confounding factors were well-balanced between the vaccine and placebo groups. This robust design provides strong evidence regarding the lack of a cause-and-effect relationship for gonorrhea prevention by the 4CMenB vaccine.