Antiretroviral pre-exposure prophylaxis (PrEP) has been shown to be safe and effective in specific populations at substantial risk of HIV acquisition, including sexually-active men who have sex with men (MSM) (iPrEx Study 1), heterosexual men and women 23 and adult injecting drug users 4. PrEP as a daily oral fixed-dose combination of tenofovir disoproxil fumarate 300mg and emtricitabine 200mg (Truvada) has been endorsed for use in the United States 5, and was made available in Switzerland in January 2016 on prescription and without reimbursement 6.

Little is known regarding PrEP awareness in Switzerland. In the Swiss cantons of Geneva and Vaud, southwest Switzerland, HIV incidence figures are among the highest in the country, with up to 12-16 new positive tests per 100,000 inhabitants in 2012 7; MSM accounted for 45% of these new infections 8. Following the results of the iPrEX Study 1, we examined PrEP awareness, experience and acceptance among MSM in this region.

The study was approved by the Ethical Commission of the Canton of Vaud (approval number 71/11) and consisted of a questionnaire-based survey conducted between 1^st June 2011 and 31^st August 2012. Trained field workers recruited individuals from 1) Checkpoint Geneva, a health centre for MSM providing counselling and screening for sexually transmitted infections (STIs), and 2) targeted meeting places, both indoor (saunas, sex clubs) and outdoor (cruising areas and Pride event).

Questionnaires, completed anonymously under field-worker supervision, covered demographic information, sexual preference, HIV status and testing history, STI history, practice of unprotected anal intercourse (UAI) and partner number in the preceding twelve months. Participants were asked if they were aware of a prophylactic treatment taken before exposure to HIV (response options: ‘very aware’, ‘slightly aware’ and ‘unaware’), if they had ever taken antiretroviral therapy (ART) to protect themselves against HIV acquisition before sex (response options: ‘yes’ and ‘no’), and if they would agree to participating in a clinical trial examining the protective efficacy of ART taken before potential HIV exposure (response options: ‘yes’ and ‘no’).

Continuous and categorical data were analysed using Student’s t-test and the Chi squared or Fisher’s exact test, respectively, using Microsoft Excel 2008 (Microsoft Corporation, Redmond, WA, USA). The percentage of individuals recruited of those approached was calculated but individuals declining to participate were not assessed.

Of 918 men approached, 654 (71%) agreed to participate, the majority of whom (536/654, 82%) were enrolled via Checkpoint Geneva (Table 1). Median participant age was 33 years (inter-quartile range 27-41 years) and 78% identified themselves as homosexual (Table 1). Of all participants, 21 (3.2%) disclosed being HIV positive, 72 (11%) had undergone recent STI treatment and 357 (55%) practised UAI. UAI without sero-sorting was reported by 76% of HIV-positive participants and was more common among individuals of positive or unknown HIV status than those of negative or undisclosed status (68% versus 43%, P<0.001).

Regarding PrEP, 110 (17%) were very aware and 164 (25%) slightly aware. Awareness was significantly higher among Checkpoint participants than those recruited from meeting places (47% versus 16%, P<0.001). There was no association with HIV status (P=0.57), STI screening history (P>0.9), UAI without sero-sorting (P=0.57) or partner number (P>0.9). Previous use of ART to protect against HIV was infrequent (10/654, 1.5%) and reported only among Checkpoint participants. There was no association with HIV status (P=0.06), STI screening history (P=0.76), UAI in the preceding 12 months (P=0.62), UAI without sero-sorting (P>0.9) or partner number (P>0.9). Finally, only 20% of participants wished to participate in a future PrEP trial. Interest was higher among individuals reporting UAI without sero-sorting (26% versus 15%, P=0.02). There was no association with STI screening history (P=0.05), UAI in the preceding 12 months (P=0.17) or partner number (P>0.9).

In this group of predominantly HIV-negative, European MSM, we observed that 42% had some PrEP awareness but PrEP experience was very low. Only 20% (132/654) were interested in participating in a future PrEP trial, against 59% (360/633) potentially eligible for PrEP (non-HIV-positive and reporting UAI and/or a recent STI diagnosis 5).

The low PrEP acceptance we observed might be related to the then non-endorsement by the Swiss federal office of public health, drug costs, and the timing of the study. Our survey was conducted between six and eighteen months after the publication of the iPrEx Study 1. An internet-based survey conducted during the month post-publication of iPrEx 9 showed PrEP awareness of 19% among American MSM, similar to our figure of 17% for participants ‘very aware’ of PrEP but lower than our figure of 42% for those with some awareness (‘very aware’ plus ‘slightly aware’). More recent studies in France 10 and Portugal 11 report MSM PrEP awareness of 41-42%.

Between 2012 and 2014, two multi-centre trials were conducted among high-risk MSM using either daily (PROUD 12) or on-demand (IPERGAY 13) PrEP. Both studies, presented at the 2015 Conference on Retroviruses and Opportunistic Infections (CROI) 1213, describe a relative reduction in HIV incidence of 86%. It is possible that PrEP awareness and acceptance would be greater were we to survey our population now, particularly if the question on acceptance were to refer to PrEP use in practice rather than within a clinical trial. Indeed, a multi-centre study of PrEP acceptance recently reported enrolment of 60.5% of 1069 eligible MSM and transgender women who were offered up to 48 weeks of tenofovir/emtricitabine as PrEP in the United States 14.

This study has limitations. Selection bias is possible, as the majority of participants were recruited from Checkpoint rather than from meeting venues, and this might have increased PrEP awareness and experience. We have no information regarding the MSM approached but not recruited, so it is not possible to quantify potential selection bias. Finally, as described above, the timing of the study in relation to subsequently published PrEP data may have led to awareness and acceptance figures which are not currently valid.

In conclusion, we observed 42% PrEP awareness and low acceptance among MSM in Switzerland after the iPrEx study, against high frequencies of UAI and UAI without sero-sorting. In the light of new data on the efficacy of daily and intermittent PrEP in high-risk MSM, PrEP acceptance in practice, as opposed to trial participation, may grow. In the meantime, and while PrEP costs are charged to the individual, measures to prevent HIV acquisition such as condom use, regular HIV screening and immediate access to ART still need to be promoted in Switzerland.