Meningococcal B Vaccine Fails to Protect Against Gonorrhea

A new randomized controlled trial (RCT) published in the New England Journal of Medicine (NEJM) has found that the Meningitis B vaccine does not prevent gonorrhea infections despite a year-long mass vaccination campaign targeting at-risk men in the United Kingdom. After gonorrhea cases exceeded the highest levels ever recorded, the U.K.’s National Health Service (NHS) decided to repurpos the meningitis B vaccine, routinely given to infants, in an attempt to reduce record-high rates of gonorrhea infections.^{1 2}

Neisseria gonorrhoeae, the bacterium that can asymptomatically colonize the oral, genital, and rectal mucusa and cause gonorrhea infections,  and Neisseria meningitidis, the bacterium that usually asymptomatically colonizes the upper respiratory tract and can, in rare cases, cause invasive meningococcal disease in genetically susceptible or immune compromised individuals.³ Both Neisseria gonorrhoeae and Neisseria meningitidis are closely related bacterial species that cause disease exclusively in humans.  They compete with each other in the human microbiome and have evolved mechanisms to evade immune defenses and develop antibiotic resistance.⁴

Gonorrhea is a sexually transmitted infection (STI) that can cause a disease that affects the genitals, rectum, and throat and most commonly infects people between ages 15-24. According to the U.S. Centers for Disease Control and Prevention (CDC), rates are highest among adolescents and young adults, although infection can occur in sexually active people of any age. Untreated, it can cause serious and permanent health problems, including pelvic inflammatory disease (PID), an increased risk of Human Immunodeficiency Virus (HIV), and can lead to infertility in both men and women. Certain complications, though rare, can be life-threatening.⁵

In describing the findings of the trial, co-lead investigator Andrew Grulich, PhD of the Kirby Institute said the results are “incredibly disappointing.” Despite hopes that the vaccine could prevent gonorrhea, Grulich explained that the “men who have received the 4CMenB vaccine in the hope of gonorrhea prevention” now know  they at least “will have protection against some meningococcal strains.”⁶

With more than 82 million new gonorrhea infections globally and incidence increasing, gonorrhea has become one of the most common STIs worldwide. As treatment has become more challenging due to drug-resistant strains of the bacteria, public health officials looked to MenB vaccines as a potential strategy to reduce infections after some observational studies showed the shot could provide “moderate cross-protection.”⁷

According to reporting from BBC, the U.K. Health Security Agency said its own studies would provide “more robust data” and, despite the newest RCT finding that the shot did not prevent gonorrhea infections, the agency is not recommending any immediate changes. The vaccination campaign, which began in August 2025, was based on a “number of studies” which they say reported a 38 percent reduction in gonorrhea infections.⁸

MenB Vaccine “Has No Effect on Preventing Gonorrhea”

The NEJM study, however, encountered vastly different results: A Feb. 2026 press release from the Kirby Institute, which led the study, said, “Contrary to existing evidence from observational studies, the meningococcal B vaccine (4CMenB) has no effect on preventing the acquisition of gonorrhea, according to the results of the world’s largest RCT into possible efficacy, conducted by Griffith University’s Institute for Biomedicine and Glycomics and the Kirby Institute at UNSW Sydney.”⁹

The press release continued:

Taken together, these two studies provide strong evidence that the 4CMenB meningococcal vaccine is not effective at preventing gonorrhea in … men who are at high risk of contracting it.

Unlike many vaccine studies conducted in the U.S., namely for routine childhood vaccines, this study used an inert placebo. “The double-blind, randomized, placebo-controlled trial involved 587 gay and bisexual men who received either the meningococcal vaccine or a saline placebo,” the press release stated.

Concerns and Serious Adverse Event Risks of MenB Vaccine

The ​​MenB vaccine is marketed under the brand names BEXSERO and Trumenba and, in the product information package insert, describes both common adverse reactions and serious adverse events observed during clinical trials, plus additional adverse events identified during postmarketing surveillance, including anaphylaxis, syncope (fainting), arthritis, blood and lymphatic system disorders, immune system and nervous disorders, extensive limb swelling, enlarged lymph nodes, severe headache, severe myalgia, and fever greater than 104 degrees F.

In one clinical study, serious adverse events were reported. However, the insert states “none of these events were considered related to BEXSERO.”¹⁰

The BEXSERO product information insert does not expand on what serious adverse events were observed in trial participants, how causality was or was not determined, or any information related to the cases. Further, any causality assessments are subjective rather than definitive and represent investigator judgments rather than proof of causation or lack of causation. Additionally, a number of adverse events were also only identified after licensure, once the vaccine was widely used.

The product information insert states, “Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to the vaccine.” The U.K. campaign represented an off-label use of BEXSERO intended to reduce gonorrhea infections.¹¹

Grulich said in an interview with CIDRAP that “these types of observational studies may be affected by confounding factors that can influence the results.” “In GoGoVax, our data demonstrate that good-quality randomization was achieved, and people randomised to receive vaccine or placebo had balanced levels of confounding factors… A properly conducted RCT provides the strongest possible evidence of a cause-and-effect relationship,” he said. When asked what these results mean for countries that continue to recommend the 4CMenB vaccine to gay and bisexual men as a strategy to prevent gonorrhea infection, Grulich said he thinks health authorities making that recommendation “should consider our findings.”¹²

There are no vaccines currently licensed for the prevention of Neisseria gonorrhoeae infection, and any campaign targeting gonorrhea prevention using MenB or other vaccines is considered an off-label use.

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