Introduction Online postal self-sampling (OPSS) is increasingly used to test for sexually transmitted infections (STIs), a trend accelerated by the COVID-19 pandemic. Whilst prior research has found OPSS to be acceptable, there remains limited understanding of how users experience OPSS compared to clinic-based services, the changes to user journeys following the introduction of OPSS, and facilitators and barriers to access. This research seeks to address these gaps, by undertaking a large qualitative study which sits within the ASSIST study, a mixed-methods, realist evaluation of OPSS.

Methods Participants were recruited via online and clinic-based sexual health services in Birmingham, London and Sheffield. People were eligible if they were aged ≥16, spoke English and had accessed participating services within the past year. Purposive sampling was used to ensure key populations – including young people, people of colour, men who have sex with men and gender minorities – were over-represented. Semi-structured interviews were analysed thematically.

Results We interviewed 100 service users. Participants expected OPSS to be easy to access and convenient, expressing high satisfaction in services where this was the case, but anxiety and dissatisfaction where expectations were not met. Although users appreciated the privacy of OPSS, and the opportunity to avoid long waits for appointments, they valued the support that in-person staff interaction offers, along with a wider range of tests available and expedited access to treatment, particularly when they perceived themselves at higher risk of having an STI. Participants found OPSS easy to use overall, aside from finger-prick blood sampling.

Discussion Our findings constitute one of the largest qualitative studies to have explored OPSS and offer valuable insights to providers. They suggest that users find OPSS acceptable, provided it operates in line with their expectations. Users also want to retain access to clinic-based services for specific circumstances, such as when they believe they have acquired an STI.