Limited drug resistance after doxyPEP but inequitable access: uptake of 4CMenB vaccine

Simon Collins, HIV i-Base

Several studies at the 6th Joint BHIVA/BASHH conference presented new data from the rollout of doxyPEP to protect against syphilis and chlamydia.

The first was a retrospective study of drug resistance against gonorrhoea from expanded access to doxyPEP, which helped allay these clinical concerns, with results presented by Martyn Wood from Liverpool University NHS Trust. [1]

Since March 2024, all culture-positive isolates for gonorrhoea (n=1416) in the Liverpool region – which has one of the highest rates of gonorrhoea – were categorised by drug sensitivity and whether or not the sample was taken before (n=875) or after (n=541) doxyPEP became available.

Although rates of resistance increased against both ciprofloxacin (38% vs 47%; p=0.001) and tetracycline (74% vs 90%; p<0.001) after the introduction of doxyPEP, the increase only normalised resistance to the national average of 46% and 91% respectively.

Importantly, no significant changes were seen for azithromycin or penicillin and no isolates were resistant to ceftriaxone.

There were no differences by sex, gender, or sexuality, irrespective of likely access to doxyPEP. However, rectal and urethral body sample sites drove the increases in tetracycline resistance.

The authors also cautioned that the changes in these observational data could not show a causal link and that the researchers interpreted the results as being supportive of the wider rollout of doxyPEP.

A second study, presented by Dana Ogaz from UK Health Security Agency, looked at equity of access to doxyPEP several months after it had been made widely available. [2]

The Reducing inequalities in Sexual Health (RiiSH) survey conducted in just over 1500 gay and bisexual men (88% white, median age 49) during November/December 2025 reported 18% had used doxyPEP.

Several factors linked to unequal access to and uptake of doxyPEP included significantly higher use in London (50% vs 35% outside London), educational status (46% of those with degree-level education vs 30% without), and if employed (43% vs 31%), all p<0.05.

However, there were no associations with ethnic group, financial comfort, physical disabilities, whether UK-born or levels of sexual satisfaction.

This study also reported that 21% of participants had already had at least one shot of the 4CMen vaccine as part of the early programme to protect against gonorrhoea. Older age was the only significant factor associated with higher vaccine access (45% among >45 year olds vs 24% aged 16-29). The presenter commented that a similar link to age was reported for the uptake of the mpox vaccine.

Acceptance of both doxyPEP and the 4CMenB vaccine was very high when they were specifically offered (at 84% and 93% respectively), showing an openness to health interventions.

Two related posters from UKHSA were also presented at the conference.

The first reported on the potential of doxyPEP to reduce syphilis and chlamydia in gay and bisexual men and trans women who have sex with men and the second estimated the numbers needed for the 4CMenB to impact rates of gonorrhoea. [3, 4]

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These data on doxyPEP suggest that this has been a broadly successful programme.

It was notable however that this session didn’t directly discuss recent data from a randomised controlled study from Australia presented at CROI 2026. [5]

However, this was raised in the Q&A afterwards when it was also noted that the Joint Committee on Vaccination and Immunisation (JCVI) still hasn’t commented on the impact these results will have on the UK’s vaccine programme.

References

Unless stated otherwise, all references are to the Programme and Abstracts of the 6th Joint BHIVA/BASHH Conference, 27–29 April 2026. HIV Medicine 2026, Supplement 1.
https://onlinelibrary.wiley.com/toc/14681293/2026/27/S1

Wood M et al. Changes in Neisseria gonorrhoeae antimicrobial susceptibility following introduction of doxycycline post-exposure prophylaxis in a large regional sexual health service. 6th BHIVA/BASHH 2026, Liverpool. Oral abstract 02.
Ogaz D et al. A new era in STI prevention: early adoption of doxyPEP and 4CMenB vaccination among a community sample of men and gender-diverse people having sex with men in England. 6th BHIVA/BASHH 2026, Liverpool. Oral abstract 05.
Migchelsen S et al. Measuring the potential impact of doxyPEP to reduce syphilis and chlamydia infections amongst gay, bisexual, and other men who have sex with men and transgender women in England. 6th BHIVA/BASHH 2026, Liverpool. Poster A111.
Harb A-K et al. Using surveillance data to estimate the number of GBMSM eligible for 4CMenB vaccination for gonorrhoea prevention in England. 6th BHIVA/BASHH 2026, Liverpool. Poster A118.
CROI 2026: Australian study of 4CMenB vaccine fails to protect gay men against gonorrhoea. HTB (10 March 2026).
https://i-base.info/htb/53465