Table 1 List of inclusion/exclusion criteria

Population: young people (aged 15–24 years) and primary care providers (PCP; general practitioners, practice nurses, nurse practitioners)

Population: exclusively on commercial sex workers, incarcerated people, people living with HIV, victims of sexual or domestic abuse or violence, intravenous drug users, and individuals with no fixed address

Randomised and non-randomised controlled trials, pre- and post-test designs, non-experiment observational (cross-sectional, case-series, case studies), qualitative (interviews, focus groups), and mixed method paper

Commentary or opinion publications that did not present new data

Conducted in countries where the model of delivering healthcare in general practice is comparable to the UK (Australia, Denmark, Ireland, Netherlands, and New Zealand) where (1) the GP acts as a gatekeeper to access specialist services and (2) general practice services are publicly financed

Conducted in countries where the healthcare system and general practice setting is not comparable to that of the UK (i.e., USA, Canada) because (1) the role of the GP in these countries differs and specialist services are readily accessible without initial GP contact and (2) most healthcare is delivered privately meaning many have to pay out-of-pocket for insurance and care. Consequently, these different systems will have distinct characteristics and influential barriers and facilitators beyond the scope of this review

Opportunistic and systematic testing in general practice

Exclusively set outside of general practice, exclusively focused on partner notification, campaigns exclusively focused on health promotion, and testing for diagnostic purposes when symptoms are present