Population-level impact of Pre-exposure Prophylaxis (PrEP) on HIV incidence in Portugal, 2012-2024

Background

Portugal maintains one of Europe’s highest HIV incidence rates (8.2 per 100000 in 2023), disproportionately affecting MSM. Despite achieving UNAIDS 95-95-95 treatment targets, prevention gaps persist. PrEP was integrated into the National Health Service in 2018-2019, reaching 7694 users by 2024. To date, no nationwide study has assessed PrEP’s population-level impact in Portugal, a setting characterized by comprehensive treatment-as-prevention coverage and still-limited PrEP uptake.

Methods

We conducted a nationwide interrupted time series analysis using mandatory surveillance data from January 2012 through December 2024 (16428 diagnoses). Segmented quasi-Poisson regression with July 2019 as the intervention breakpoint was used to estimate immediate level changes and slope modifications. Stratified analyses explored heterogeneity by transmission mode, nationality, age group, and geographic region.

Results

A pre-existing 5.5% annual decline was observed (RR = 0.9953, p < 0.001). Following PrEP implementation, an 11% immediate reduction occurred (RR = 0.89, p = 0.060) with mean monthly diagnoses declining from 122.2 to 82.3. Stratified analyses revealed significant reductions among MSM (RR = 0.85, p = 0.015), Portuguese nationals (RR = 0.83, p = 0.003), and individuals aged 15-24 years (RR = 0.69, p < 0.001). No effects were observed among non-Portuguese nationals (RR = 1.02, p = 0.770) or Lisbon metropolitan region (RR = 0.95, p = 0.465) despite concentrated services.

Conclusions

PrEP generated benefits among target populations with direct access. Observed heterogeneity appears consistent with structural barriers affecting migrants and geographic disparities. In Portugal, the hospital-centred delivery model may have constrained equitable territorial reach. Policy changes include integration into primary care, expansion of community-based distribution, culturally adapted services, and strengthened confidentiality and access guarantees, irrespective of administrative status.

Key messages

• Portugal’s PrEP program reduced HIV diagnoses significantly among MSM, Portuguese nationals, and youth, but overall modest impact reflects insufficient coverage.

• Disparities in PrEP effectiveness across populations reveal implementation barriers that must be addressed to achieve equitable HIV prevention and epidemic control.