Two readers responded to my question on evidence on the effectivness of TasP and PrEP on bloodborne transmission of HIV. I asked: "Do any readers know of any evidence that #PrEP is effective at preventing bloodborne HIV transmission among people who inject drugs (#PWID).

Do any readers know of any evidence that Undetectable = Untransmissible (U=U, #UEqualsU) is effective at preventing bloodborne HIV transmission among people who inject drugs?"

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1) For your information, consider the JIAS Commentary: the value of PrEP for people who inject drugs - Europe PMC Article - Europe PMC.

"PrEP is best understood as an additional potential HIV prevention option for some people who inject drugs and their sexual partners in specific circumstances. The challenge is to ensure that the potential of PrEP is not undermined by narrow and overly biomedical understandings of its value, removed from the real lives of those most at risk of HIV exposure."

Source: J Int AIDS Soc. 2016; 19 (7Suppl 6): 21112. Published online 2016 Oct 18.

http://europepmc.org/articles/pmc5071747

Also it is evident that the voice and the PWID community perspective is critical and ought to be centre in decision-making.

Check-out below most helpful nuanced INPUD background document from March 2015; 'An Introduction to Pre-Exposure Prophylaxis (PrEP) for People who Inject Drugs: pros, cons, and concerns @
http://www.inpud.net/en/pages/key-publications

2) Direct evidence is limited – only 1 PrEP trial with PWID and no specific studies on early treatment and prevention. But the biological evidence is incontrovertible and there is no biological reason why viral suppression or PrEP would not be equally efficacious for prevention of transmission or acquisition, respectively, among PWID.

WHO PrEP guidelines clearly recommend PrEP for anyone at risk (there is no distinction in relation to why they are at risk) and it is the same for U=U messaging internationally.

Above points are about efficacy, but the real issue is effectiveness. Is there a difference in the real world in how effective PrEP or early treatment are in preventing HIV transmissions among PWID compared to other groups.

This may well vary, but only because of the social, legal and physical environments in which PWID live and in which injecting drug use occurs. Ultimately, if there is reduced effectiveness it will be because of the marginalisation of PWID within health care settings and within the community that makes it difficult for PWID to adhere to medication.

I hope this stimulates some discussion. I would not prescribe PrEP to prevent bloodborne transmission of HIV and would not tell a patient that U=U for people who share injecting equipment.

Jamie