CROI 2026: Australian study of 4CMenB vaccine fails to protect gay men against gonorrhoea

10 March 2026. Related: Conference reports, Coinfections and complications, CROI 33 (Retrovirus) 2026.

Simon Collins, HIV i-Base

One of the controversial studies presented at CROI 2026 included unexpected results showing no protection from two doses of the 4CMenB meningococcal B vaccine against against gonorrhoea in gay men at high risk of STIs. [1]

Earlier results from observational studies showed a roughly 30 to 40% reduction in incidence of gonorrhoea. [2, 3]

This led to NHS England last August recommending the vaccine for gay and bisexual men and sex workers at high risk of STIs based on a decision by the UK Joint Scientific Committee on Vaccination and Immunisation (JCVI) in November 2023. [4, 5]

The GoGoVax study at CROI 2026 was presented by Kate Seib from Griffith University Southport Australia. This double-blind, placebo-controlled multisite study randomised more than 600 gay men aged 18 to 50 to receive either two doses of the 4CMenB vaccine, given three months apart, or placebo.

Entry criteria included HIV-negative men to be on PrEP and HIV-positive men to be on effective ART and to have had a gonorrhoea diagnosis in the previous 18 months. Monitoring included urogenital, anorectal and oropharyngeal swabs every three months for two years, with the primary endpoint based on time to the first detection of gonorrhoea.

This was a largely HIV-negative study (90%), with mean age 34 (+/– 6), and 90% had a history of gonorrhoea and 19% of syphilis. 60% reported more than 10 partners in the last 6 months (and 6% more than 50 partners; one third didn’t routinely use condoms with casual partners).

The incidence of infection (per 100 person-years) was 48.1 (in 160/296) vs 47.8 (155/291) in the 4CMenB vs placebo groups respectively (IRR: 1.01; 95%CI: 0.80 to 1.25; p=0.97). This produced a vaccine efficacy of –0.5% (95% CI: –26 to +19%).

Results were similar and showed no benefit in subgroup analyses for both symptomatic and asymptomatic infections and for all three body sites.

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This study generated significant discussions in the open Q&A session after the presentation, including whether an additional vaccine dose might help, or whether behaviour change might have been a factor (it wasn’t).

The presenter optimistically suggested the importance of waiting for results from other ongoing studies, including in women and lower incidence populations. [5, 6, 7]

However others, including Jean-Michel Molina (PI for the French ANRS 174 DOXYVAC study), thought it unlikely that any systemic protection from a vaccine would lead to protection against mucosal infection at different sites, and that this would require a better vaccine. DOXYVAC also reported no benefit from the 4CMenB vaccine in a similar population. [8]

The UK JCVI have not commented yet on whether the current vaccine programme will continue or not, but they will need to respond to the new results. 

Until this decision is announced, some UK doctors are waiting to see results from other studies before recommending the 4CMenB vaccine. [9]

Although the vaccine will protect against meningococcal B, it is not without side effects, anecdotally feeling like a hard punch to the harm that can persist for a week.

References

1. Seib KL et al for the GoGoVax Study. Meningococcal B (4CMenB) Vaccination for the Prevention of Gonorrhea in Men Who Have Sex With Men. CROI 2026, Denver. Oral abstract 197.
2. Taylor K. Gonorrhoea vaccine might halve infections and help combat drug resistance. HTB (1 July 2022).
   https://i-base.info/htb/43236
3. Ladhani SN et al. Use of a meningococcal group B vaccine (4CMenB) in populations at high risk of gonorrhoea in the UK. Lancet Inf Dis 24(9):9E576-E583. DOI: 10.1016/S1473-3099(24)00031-8. (30 March 2024).
   https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(24)00031-8/fulltext
4. UKHSA. A guide to the Meningococcal B vaccine for protection against Gonorrhoea. Updated 28 July 2025.
   https://www.gov.uk/government/publications/meningococcal-b-menb-vaccination-against-gonorrhoea-guide/a-guide-to-the-meningococcal-b-vaccine-for-protection-against-gonorrhoea
5. Safety and Efficacy Study of Meningococcal Group B Vaccine rMenB+OMV NZ (Bexsero) to Prevent Gonococcal Infection. NCT04350138.
   https://clinicaltrials.gov/study/NCT04350138
6. BIYELA – Bexsero Immunisation in Young Women in Africa. NCT06446752.
   https://clinicaltrials.gov/study/NCT06446752
7. Efficacy of Immunization With 4C-MenB in Preventing Experimental Urethral Infection With Neisseria Gonorrhoeae. NCT05294588.
   https://clinicaltrials.gov/study/NCT05294588
8. Molina JM et al for the ANRS 174 DOXYVAC Study Group. Doxycycline prophylaxis and meningococcal group B vaccine to prevent bacterial sexually transmitted infections in France (ANRS 174 DOXYVAC): a multicentre open-label randomised trial with a 2 × 2 factorial design. Lancet Infect Dis. 2024 Oct 24(10):1093-1104. doi: 10.1016/S1473-3099(24)00236-6.
   https://pubmed.ncbi.nlm.nih.gov/38797183
9. BHIVA. Best of CROI 2026 Feedback webinar. 17 March 2026.
   www.bhiva.org