PrEP and preventing HIV infection


Sir, – As a medical doctor, I must disagree with Derek Byrne on the subject of HIV pre-exposure prophylaxis (PrEP) for men who have sex with men (MSM) (“Anti-HIV drug removes personal responsibility”, Opinion & Analysis, April 20th). Mr Byrne refers to (without referencing) “research” which shows the effectiveness of PrEP at preventing HIV as being somewhere between 40 per cent and 70 per cent. In fact, the largest PrEP study to date (McCormack, et al, The Lancet, 2016), showed an 86 per cent reduction in incidence of HIV infection amongst those taking the drug. Furthermore, all three study participants who contracted HIV while taking the drug (as against 272 who remained uninfected) were shown to have taken the drug inconsistently. This suggests that, correctly taken, PrEP is likely to be far more than 86 per cent effective.

Another large trial, looking at PrEP taken on a less than daily basis, also showed an 86 per cent reduction in infections (Molina, et al, New England Journal of Medicine, 2015).

Neither trial found evidence of an increased rate of serious-side effects, such as the “widespread liver disease” Mr Byrne fears. Incidentally, PrEP acts on the kidney, not the liver, and for the most part it did not affect that either.

Mr Byrne feels that PrEP “removes personal responsibility” from the equation. I would argue that it empowers MSM to take responsibility for their own health, in much the same way as contraceptive pills empower women.

It is a major medical breakthrough, which needs to be taken off the somewhat dodgy online pharmacies, and put in the hands of patients via their doctors, at an affordable price. – Yours, etc,


Ballymun Family Practice,

Dublin 9.