Hancock E, Ward Z, Ayres R, et al. - Given that larger volume of blood is retained when people who inject drugs (PWID) use traditional detachable syringes with depressed plunger vs syringes with fixed needles; these syringes are referred to as high (HDSS) and low dead space syringes (LDSS), respectively. Evidence infers that hepatitis C virus (HCV) transmission risk is greater when using HDSS vs LDSS. In this work, the cost-effectiveness of an intervention to introduce detachable LDSS in a needle and syringe programme (NSP) was determined. Among PWID attending NSP, researchers performed gradual replacement of HDSS, with 8%, 58% and 95% of HDSS being replaced by detachable LDSS in 2016, 2017 and 2018, respectively. Comparator was continuing use of HDSS. A small increase in intervention costs (£21,717) was observed in correlation to the introduction of detachable LDSS compared with not introducing detachable LDSS, but with significant savings in HCV-related treatment and care costs (£4,138,118). In needle and syringe programs in the United Kingdom, replacing high dead space syringes with detachable low dead space syringes seemed to be a cost-saving approach for decreasing hepatitis C virus transmission.