The first evidence for the effectiveness of PrEP in the real world is out – and it’s good. Of over 600 men prescribed the HIV-prevention treatment for the past two and a half years, there have been ZERO new HIV infections.

Truvada, the medication currently used as PrEP.
Truvada, the medication currently used as PrEP.

PrEP – short for pre-exposure prophylaxis, a drug regime intended to prevent HIV infection – has been under intense study for a number of years now. All these studies have concluded that PrEP is both safe and effective at reducing – drastically reducing – HIV infections. Given the overwhelmingly positive results of these trials, PrEP has been available in the United States for a number of years now.

Thanks to this availability, it has now been possible to examine how effective PrEP is in the ‘real world’, outside the somewhat artificial environment of a clinical study. That is exactly what this new research – published in the journal Clinical Infectious Diseases‘ –  set out to do, following 657 men in San Francisco over a two year period and concluding that, despite high sexual activity in the group, not one of them had been infected. Mitchell J. Warren, executive director of the HIV advocacy group AVAC, commented that the study “fills in a critical gap by showing that PrEP can prevent infections in a real-world public health program”.

In the study, the majority of individuals prescribed PrEP were gay men who engaged in sex with multiple partners, putting them at ‘high risk’ of HIV transmission. While the headline figure of no HIV infections is an even better result than expected, around 40% of those prescribed PrEP reduced their condom use  – which was surprising (previous findings indicated that people on PrEP treatment would not change their condom use).

Rates of other infections were high; after a year, 50% of PrEP users were diagnosed with at least one STI, including two cases of hepatitis C. As this wasn’t a true clinical study, it is impossible to know what the STI infection rate would be had these individuals not been on PrEP. As noted, individuals prescribed the treatment tended to be ‘high risk’, and the treatment programme itself involved regular STI testing. However, it is clear that PrEP should work alongside, rather than replace, community sexual health monitoring and treatment.

Echoing this sentiment, a hopeful commentary from the journal comments that ‘feeling safer from HIV infection while using PrEP creates space for a more robust discussion of STIs’.

More research of this kind will be needed to be certain of just how effective PrEP is ‘in the wild’. Furthermore, as PrEP is increasingly prescribed in different communities and countries, it will be important to asses how it is used and how effective it is in each of these areas; gay men in San Francisco may not be representative of other groups.

However, this encouraging data adds to the already voluminous clinical trial data which strongly supports the use of PrEP in tackling HIV. It is certain to add to growing calls from HIV advocacy groups and sexual health clinics for PrEP to be made available in the UK without delay.

Phil Hoggart Header


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