Should we worry about the effect of PrEP on STI rates?

Yusef Azad
29th March 2017

One argument you see amongst those critical or worried about the introduction of PrEP is that it will result in big increases in STIs as gay and bisexual men (and indeed others at risk of HIV) throw away their condoms.  But does the evidence support such fears?  And as importantly, what do those fears tell us about our views of HIV and gay sexual health?

1. The data

A review of a number of studies of PrEP and STIs found much higher rates of STIs amongst gay men using PrEP compared with gay men not using PrEP.i  But that is what you would expect and indeed want.  PrEP is for people at high risk of HIV, and thus also of other STIs. What these studies do not show is that taking PrEP makes these gay men less likely to have safer sex and more likely to get an STI than would otherwise be the case.

The STI rate indicates that the right people are accessing PrEP - not the 'worried well' but those who are at high risk of HIV if PrEP is not used.

It’s also worth remembering that some of this higher rate of STIs among PrEP users can be explained by the fact that they are testing for STIs much more regularly than non-PrEP users – which means more diagnoses.

There is, however, other data emerging to suggest PrEP use can be associated with some shifts in condom use and increase in STIs. Whilst the PROUD study in the UK showed no statistically significant difference in rectal STI rates between the PrEP and non-PrEP arms, there was some increase in numbers of receptive condomless sex partners reported amongst men in PROUD who already at the start of the trial were reporting a lot of condomless sex.ii

There is also a San Francisco study which asked about trends in condomless sex (the same amount, more, or less) after up to 16 months on PrEP and saw over time a growing proportion of men on PrEP reporting an increase in condomless sex.iii

A study from Northern California has also shown an increase in STI diagnosis rates of those on PrEP, though notes this may be the result of increases in testing frequency or sexual behavioural changes.iv

A final point on the data. From some of the debate you'd think that in the absence of PrEP there were no STIs around!  But we already have an STI crisis amongst gay men – and it started a long time before PrEP was on the scene. Just looking at the UK data from Public Health England for new STI diagnoses among gay men between 2011 and 2015 we see a 64% increase in annual numbers diagnosed in sexual health clinics with chlamydia (94% in London); a 179% increase in annual numbers diagnosed with gonorrhoea (209% in London); and a 103% increase in new diagnoses of syphilis (127% in London).

The main community initiatives enabling wider access to generic PrEP from overseas – Iwantprepnow and Prepster - only launched towards the end of October 2015 – far too late to influence any of this data.

Improved STI testing technologies and practice can explain some of this increase, but Public Health England is clear that increasing risk behaviour is a key driver. Not providing PrEP does nothing to address the real issue of gay men and STIs - it simply keeps men at risk of the most serious of them, HIV.

So I think to be true to the data, we must say:

High rates of STIs among men who use PrEP indicate their need for PrEP and the fact that PrEP is being accessed by people who already, prior to any PrEP access, use condoms inconsistently and are vulnerable to STIs. This is in the context of massively increasing STI rates among gay men, again taking place prior to and independently of any PrEP use. There is an STI crisis to address - it has nothing to do with PrEP and not providing PrEP will do nothing to address it.

Having said that, there is some emerging evidence that there is some shift away from condom use and increase in STIs once men start using PrEP. But, very importantly, these shifts are not massive and are amongst men who already have inconsistent condom use and high STI rates. PrEP is not 'luring' men who use condoms consistently and never get STIs into risk-taking behaviours. So there may be a marginal impact around risk amongst men already at significant risk. This is not to be simply waved away and ignored of course - it underlines the need for PrEP to be provided within a package of risk reduction measures and support. But it is in no way significant enough an effect to counterbalance the immense gain of so many men not acquiring HIV or passing it on.

2.  The arguments

a. You cannot 'uninvent' PrEP

Sometimes anti-PrEP arguments sound like a debate as to whether or not we should discover/invent PrEP in the first place! But it exists; gay men know it works; and in the absence of appropriate provision on the NHS high numbers are already accessing PrEP generically online (or in some other, possibly more risky, ways). Whether we like it or not, PrEP is here and we need to live with its impacts, whether positive or negative. Refusing through unfounded fear of STIs to provide PrEP on the NHS only means denying PrEP to men who need it but don’t have the knowledge, money or incentive to access it online from overseas. This is fundamentally unjust and entrenches health inequalities.

b. PrEP access can link men at risk into wider healthcare, including STI testing and treatment

As and when PrEP is provided in England you will access it on the NHS through prescriptions every three months in sexual health clinics, which are accompanied by STI tests and support around safer sex. Thus, PrEP offers the opportunity for timely, prompt STI treatment. Prompt STI treatment cuts chains of transmission, ensuring STIs are treated before the individual has the chance to pass them on to many other partners (who would themselves pass them on … etc etc).

PrEP also provides the opportunity for interventions to promote condom use. It is a serious mistake to see PrEP as provided 'in opposition to condoms' - health promotion messages and practice can readily promote a combination prevention approach and link men into regular sexual health care and support.

c. What would happen if we found a vaccine for HIV, or a cure?

I often ask those who dislike PrEP and talk of impacts on condom use and STIs, whether they would oppose vaccination of men against HIV if a vaccine became available, or oppose the provision of a cure for those who have HIV, should we discover a cure. The logic is the same. What would then happen to condom use and STIs? PrEP has exposed our shortsighted reliance for decades on fear of HIV as the only reason for men to maintain their sexual health. In a strange way this is just another example of HIV stigma - loading HIV with a meaning and function it should not have to bear.

Relying on fear of HIV as our only strategy against other STIs no longer works. We have run out of road. And thank goodness for that – it’s because our fight against HIV transmission is increasingly effective and hopeful (though not over yet!).

A new challenge is on the horizon. Talking about STIs, our sexual health, and indeed our well-being generally, without HIV being the dominant (or indeed only) reference-point. The new landscape is disorientating. But the community efforts which have produced such wonderful results in fighting HIV can now also be as productively focused on the many other health issues facing gay men – on STIs, on mental health, on problematic drug and alcohol use, on smoking. There is more work to do.  There are more successes to be achieved.

Thanks to Roger Pebody at NAM for talking through the evidence on PrEP and STIs over the last few months

iii It should be noted, however, that over time an even greater proportion of men discontinued PrEP use, presumably for the most part because their period of less safe sex had ended
iv see also IPERGAY data reported at