PrEP for STIs – Is biomedical STI prevention within our reach?

By Chris Williams, updated 7 months ago in Health / Sexual health

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Could there be a pill to prevent STIs? What was once unimaginable as a concept is already fast becoming an unprecedented success when it comes to using prescription medicine to prevent HIV. But is there any hope of a medical breakthrough to address the growing STI epidemic? Yes, there could be…

In just a few years, Australia has gone from being barely aware of PrEP as a biomedical HIV prevention strategy, to it being available nationwide as a government subsidised medicine. PrEP’s rapid and widespread uptake by gay and bisexual men in particular is testament to its desirability and convenience as a highly effective addition to the HIV prevention toolkit.

But as is often rightly pointed out in healthy discussions about this groundbreaking innovation in sexual health medicine, PrEP offers extremely good protection against HIV and doesn’t offer any biomedical protection against other STIs.

Of course, PrEP is much more than just a pill. It’s a strategy for comprehensively managing sexual health and wellbeing, which includes HIV and STI testing every three months as standard. While modelling estimates predict increased PrEP uptake would likely lead to an overall reduction in STIs in the long run, regular testing alone only forms part of the “prevent, test, treat” mantra of health agencies.

Innovative interventions

The more we learn about how STIs are transmitted, the more apparent it’s becoming we need to urgently pursue additional approaches for proactively preventing them — beyond the strengths (and limitations) of the mighty condom. One such learning is the fairly recent discovery that saliva could be the main driver of gonorrhea transmission — kissing is estimated to account for nearly three quarters of all cases of gonorrhea in men who have sex with men.

And while research indicates it’s unlikely many of us will be enthused to prevent oral transmission by refraining from a good pash, studies into using antiseptic mouthwash every day could yield a possible solution yet — though considerable research is required before this could be recommended for any medical intervention beyond the benefits of minty fresh breath.

“…kissing is estimated to account for nearly three quarters of all cases of gonorrhea in men who have sex with men.”

But mouthwash isn’t the only novel solution for the spread of STIs under scientific scrutiny. While we patiently await the development of STI vaccines, enter broad-spectrum antibiotic, doxycycline.

Promising results

Now, it’s understandable that after being exposed to clickbait about the impending apocalypse from non-essential use of antibiotics, you might be a little apprehensive about their use as a preventative medicine. Being cautious about how we take advantage of biomedical technologies isn’t a bad thing. But neither is using the tools we have in safe and responsible ways under guidance from medical professionals.

It’s still early days for research into the possibility of using antibiotics to prevent STIs, even though we’ve been using them to treat STIs successfully for much longer. So far, two studies involving doxycycline have showed promising results for offering some degree of protection against some STIs.

First up was a small pilot study in 2015 involving 30 people living with HIV — the study found that participants who were given doxycycline were 70 per cent less likely to acquire an STI than those financially incentivised to use other forms of STI prevention.

The second study took place in 2016 involving 232 HIV-negative men and trans women — the results showed that using doxycycline demonstrated a risk reduction of 70 per cent for syphilis and 73 per cent for chlamydia, though it didn’t show any risk reduction for gonorrhea.

Legitimate concerns

These results are promising, especially for chlamydia and syphilis. Chlamydia is the most commonly diagnosed STI in Australia and cases of syphilis more than tripled between 2010 and 2016.

So does that mean we should all start taking doxycycline as soon as we can? No — but it does yield some hope for the possibility of extending our current options for STI prevention. Because right now, other than physical barrier devices such as condoms, we just don’t have many effective ways to prevent STIs.

“Being cautious about how we take advantage of biomedical technologies isn’t a bad thing.”

In spite of promising results, there are legitimate concerns with using antibiotics this way. In theory, regular and widespread population use of an antibiotic could lead to antibiotic resistance — meaning the very STIs we’d be trying to prevent could become drug-resistant infections no longer effectively treated by those particular antibiotics, limiting available treatment options. And while doxycycline is typically well-tolerated by most people, it can result in increased photosensitivity (skin sensitivity to sunlight) and possible stomach upsets.

However, it’s also important to consider that the benefits of reducing the risk of acquiring chlamydia or syphilis potentially outweigh the harms of some people using doxycycline intermittently — rather than using doxycycline every day, the 2016 study had participants take just 100mg (two pills) within 24 hours after sex, and no more than six pills per week.

The take-away

Although these developments make it seem as if the dawn of biomedical STI prevention could be within our reach, for now, the use of antibiotics to prevent STIs remains under careful investigation. Legitimate concerns from medical professionals must be explored in more detail, along with community attitudes towards the possibility of adding yet another pill to what is, for some of us, already a sizeable dose to swallow.

While doxycycline may offer some promise as an additional tool for preventing STIs, it’s unlikely to be right for everyone. Commentary from clinicians around the use of doxycyline suggests it would most likely be more suited to highly sexually active people with multiple partners who may not always use condoms.

“…right now, other than physical barrier devices such as condoms, we just don’t have many effective ways to prevent STIs.”

But if we’ve learned anything from the immense success of PrEP for HIV, it’s that biomedical solutions don’t just help protect us at a cellular or microbial level. They also have the ability to protect us at an emotional level, safeguarding us from fear and fostering our confidence to connect with one another.

Until the evidence comes in for using doxycycline, mouthwash or any other innovative developments in STI prevention, we suggest the use of a simple latex tool — otherwise known as a condom — as a way to help prevent many of these unwanted infections.