Sex work amongst people who inject drugs in England, Wales and Northern Ireland: Findings from a National Survey of Health Harms and Behaviours

•One in seven PWID in EW&NI had a lifetime experience of sex work.•Sex work was found not to be associated with blood-borne viral infections.•SWs were significantly more vulnerable due to imprisonment and homelessness.•Harm reduction service provision needs to be maintained to reduce transmission of BBVs.•Services need to cater for the gendered differences in vulnerabilities amongst PWID.