HIV incident infections during pre-exposure prophylaxis (PrEP) use in Wroclaw, Poland, 2017-2023: a real-life experience.

Objectives: The efficacy of pre-exposure prophylaxis (PrEP) relies on adherence to effective regimens. As data on real-life PrEP roll-out and efficacy from Central and Eastern Europe are scarce, we explored the HIV incident infections among PrEP users in an observational cohort in Poland.

Methods: A cohort of 887 men having sex with men (MSM) on generic emtricitabine/tenofovir disoproxil (FTC/TDF) were followed for a cumulative 2587 person years (PY). HIV infection was confirmed using molecular and immunoassays, with subtype and genotyping performed at diagnosis. For phylogenetic analysis, we used 2087 HIV-1 A6 partial pol sequences from Poland as background.

Results: Nine (1%) PrEP users acquired HIV during the follow-up period. The estimated HIV incidence was 0.347 per 100 PY, with a relative risk reduction of 90.9%. All users who acquired HIV were cisgender white MSM of European origin (median age: 35.5 years). The majority (eight out of nine) used PrEP on demand (ie, 2-1-1 schedule), with one using PrEP only before receptive and not insertive sexual contacts and seven skipping the double dose. Infections occurred due to inadequate PrEP dosing. In five (55.6%) and four (44.4%) users, subtypes B and A6 were acquired, respectively, with no drug resistance. Each of the four A6 sub-subtypes belonged to distinct clusters. Three of them had distinct regional origins within Poland and one in Ukraine. Users were started on tenofovir alafenamide/emtricitabine/bictegravir at a median of 10.5 days from diagnosis and reached undetectable viral load (<50 copies/mL) at a median of 63 days.

Conclusions: Overall, FTC/TDF PrEP was very effective, with failures occurring due to suboptimal adherence to on-demand dosing. Effective communication of HIV-related risks and clear instructions on how to use on-demand PrEP without missing doses should be provided to PrEP users. Despite the lack of transmitted drug resistance, we noted a higher number of infections with the A6 subtype and independent lineage introductions.