Purpose of review: This review examines evidence regarding the differential effects of high dead-space syringes (HDSS) and low dead-space syringes (LDSS) on HIV transmission among people who inject drugs (PWID). It also identifies areas for additional research and examines potential barriers to interventions that promote LDSS.
Recent findings: Results of laboratory experiments and cross-sectional bio-behavioral surveys provide circumstantial evidence that the probability of HIV transmission associated with sharing LDSS is less than the probability of HIV transmission associated with sharing HDSS. Mathematical models suggest that LDSS may prevent injection-related HIV epidemics among PWID.
Summary: Circumstantial evidence suggests that LDSS may substantially reduce HIV transmission among PWID, who share syringes. Additional research that links LDSS to reductions in HIV incidence is needed. Most currently available LDSS are 1 ml or smaller and have fixed needles. These cannot be used by PWID 'injecting' larger volumes of fluid and they may be rejected by PWID, who prefer syringes with detachable needles. Nonetheless, LDSS represent a potentially promising intervention that deserves serious consideration.