Healthcare provider workload assessed via a short survey measuring perceived workload and time burden, assessed using a standardised Likert-type scale (1-5); higher scores indicate greater perceived workload.

Number of newly diagnosed HIV and STI cases identified through the free voluntary counselling and testing visits across participating sites per reporting period.

Number of participants who received an STI or HIV diagnosis during the pilot project and subsequently received treatment, defined as antibiotics dispensed at a pharmacy or attendance at a medical appointment at Maihof Praxis Lucerne or Checkpoint Zurich.

Participant-reported comfort regarding sexual health (encompassing physical, emotional, and social wellbeing related to sexuality and relationships), measured on a visual analogue scale from 0 (not comfortable) to 100 (very comfortable). Filled in at clinic while waiting for appointment and again approximately 1 week after the appointment.

Testing behaviour assessed via administrative data and self-report. Participants indicate whether this is their first STI/HIV test and, for HIV testing, time since last HIV test. Trends in testing frequency are monitored over the study period.

Participants rate 12 topics on a scale from 1 to 5 (1=never heard of it, 5=very familiar); higher scores indicate greater knowledge. Participants rate their familiarity at the clinic prior to the appointment and approximately 1 week after the appointment. The measure is the change between pre- and post-appointment rating.

Knowledge assessed using 8 true/false items (total score range: 0-8), administered at the clinic prior to the appointment and again approximately one week post-appointment. Higher scores indicate greater knowledge. The measure is the change in score from pre- to post-appointment.

Self-efficacy and attitudes assessed using 13 items rated on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree), administered at the clinic prior to the appointment and again approximately one week post-appointment. Higher scores indicate greater self-efficacy and more positive attitudes. The measure is the change in score from pre- to post-appointment.

Information-seeking behaviour is assessed using a multiple-choice question identifying sources of sexual health information (e.g., internet, healthcare provider, peers). Reported descriptively as frequency and distribution of sources selected; administered at the clinic prior to the appointment only.

Proportion of participants holding a KulturLegi card (indicating low-income eligibility) among all enrolled participants; reported descriptively.

Proportion of KulturLegi card holders enrolled in the study relative to the total number of KulturLegi cards issued in the catchment area during the study period. Assessed by comparing observed reach against a pre-specified target of ≥5% of the eligible low-income population.

STI/HIV positivity rates, re-testing rates, and knowledge scores compared between low-income eligible participants (KulturLegi card holders) and age-eligible participants. Differences between groups are reported descriptively; regression modelling may be applied to explore associations and inform policy decisions.