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Can Low Volume Syringes Help End HIV and HCV Transmission Among People Who Use Drugs?

Syringes that have a lower "dead space" volume retain less fluid that can harbor HIV and hepatitis C virus (HCV), and switching to this type could help reduce viral transmission among injection drug users, according to an article in the January 2013 issue of International Journal of Drug Policy.

Researchers at RTI International and the Futures Institute propose that changing the type of syringes made available in areas where the local HIV epidemic is injection-driven may lower and eventually halt HIV transmission among people who inject drugs.

The key may lie in the difference between high dead-space syringes (HDSS) and low dead-space syringes (LDSS). Dead-space refers to the parts of a syringe where blood and other fluid remains after the plunger has been fully depressed. In contrast with high dead-space syringes -- which have detachable needles and retain an average 84 mcl of fluid when expressed -- low dead-space syringes generally have permanently attached needles and only retain an average 2 mcl of fluid in the needle itself.  

Thus, a person who shares a high dead-space syringe with an HIV positive partner is more likely to be exposed to the virus than those who use a low dead-space syringe.   

In laboratory experiments simulating the process of aspirating blood into the syringe and rinsing it out with water, high dead-space syringes retained 1000 times more HIV than low-dead space syringes. In similar experiments testing for hepatitis C, low-dead space syringes were also shown to be less likely to transmit the virus. Studies showed that HCV was only able to live for 1 day in a low dead-space syringe, as opposed to 60 days in a high dead-space syringe.  

Using a mathematical model, the authors projected that replacing high dead-space syringes with low dead-space syringes in countries with injection-driven epidemics -- such as China, Indonesia, Russia, and Ukraine -- would lead to major reductions in HIV transmission, with a foreseeable outcome of reducing transmissions to nearly zero within 8 years.  

A survey of current HIV rates across cities with high levels of injection drug use seems to support this claim. In countries where high dead-space syringes are mostly used, HIV prevalence was low among people who inject drugs in 18 cities, moderate in 15 cities, and high in 25 cities/areas. In cities/areas where low dead-space syringe are most common, HIV prevalence was low in 8 cities/areas and high in only 1 city.  

Further research is required, but the authors highlight the need for prompt feasibility studies and randomized controlled trials, as well as rapid assessments with people who inject drugs to identify potential barriers in practicality.

"Although additional research is needed, this intervention should be implemented and evaluated as soon as possible," stated lead author William Zule. "Switching from high dead-space to low dead-space syringes should be viewed as an additional component to comprehensive HIV prevention packages."

A low-cost initiative, the primary concern is the difficulty of getting the word out to educate drug users, care providers, and pharmacists about the reasons for making this change. Another potential barrier is that most low dead-space syringes have a shorter barrel and permanently affixed needles, which will not work for injecting drugs that must be dissolved in a larger volume of liquid. Drug users may also often prefer detachable needles, as they can be replaced if they become clogged. There is currently only 1 manufacturer of low dead-space detachable needles, which are expensively priced.

Despite these potential obstacles, drug user advocates have heralded this study. "This study makes a compelling case for syringe access programs to review their policies and education," said Daniel Raymond, Policy Director for the Harm Reduction Coalition. "Globally, a switch to low dead-space syringes has the potential to reduce not only HIV infections, but also hepatitis C infections among people who inject drugs."

Zule states that he is collaborating with the North Carolina HIV/AIDS division to disseminate education within the community, and moving forward from there to gather information about the types of syringes used in the U.S. and working towards a national shift to using low dead-space syringes.  

1/18/13

Reference

WA Zule, HE Cross, J Stover, and C Pretorius. Are major reductions in new HIV infections possible with people who inject drugs? The case for low dead-space syringes in highly affected countries, International Journal of Drug Policy 24(1):1-7.January 2013.

Other Source

RTI International.  Better Syringe Designs Could Nearly Eradicate Global Annual HIV Infections from Syringe Sharing Within 8 Years. Press Release. January 16, 2013.