• Posted March 20, 2026

Meningitis Vaccine Doesn't Protect Gay, Bisexual Men From Gonorrhea, Clinical Trial Concludes

A meningitis vaccine does not protect against gonorrhea spread between men, a new clinical trial has concluded.

Experts had hoped that a meningococcal B vaccine called 4CMenB might prevent the spread of gonorrhea, based on an earlier study that linked the vaccine to a 38% reduced risk of the sexually transmitted infection.

But a clinical trial designed to prove this effect instead found that gonorrhea rates were the same between men who got either the vaccine or a placebo jab, researchers reported at a Conference on Retroviruses and Opportunistic Infections held in Denver.

“Across both arms, the gonorrhea incidence was virtually the same – at around 48% per year, indicating very clearly that the vaccine had no effect on preventing gonorrhea,” lead researcher Kate Seib, a professor at Griffith University in Australia, said in a news release.

The results “provide strong evidence that the 4CMenB meningococcal vaccine is not effective at preventing gonorrhea in gay and bisexual men who are at high risk of contracting it,” Seib concluded.

There remains no vaccine to protect against gonorrhea, researchers said. Antibiotic-resistant strains of gonorrhea have started to emerge, increasing the need for a vaccine.

For the study, researchers recruited 654 men who have sex with other men, and the primary analysis included 587. Half were randomly assigned to receive the meningococcal vaccine and the other half a placebo.

Tracking across two years showed that the vaccinated men had the same odds of contracting gonorrhea as those who’d gotten the placebo.

Researchers suspect that the earlier study’s results likely were confounded by other factors not related to the vaccine.

“An effective vaccine to reduce gonorrhea would transform our approach to prevention, so it is incredibly disappointing that our research has proven that 4CMenB is not effective in gonorrhea prevention in gay and bisexual men,” said researcher Andrew Grulich, a professor at the Kirby Institute at the University of New South Wales in Australia. 

“We want men who have received the 4CMenB vaccine in the hope of gonorrhea prevention to know that the vaccine is very safe and they will have protection against some meningococcal strains,” Grulich said in a news release. “However, these men will need to explore other options for prevention of acquisition of gonorrhea, such as condoms and regular testing.”

Seib presented these findings on Feb. 25 at the scientific meeting in Denver.

Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

The U.S. Centers for Disease Control and Prevention has more on the meningococcal B vaccine.

SOURCE: University of New South Wales, news release, Feb. 25, 2026