Harm reduction includes many strategies, such as methadone maintenance, needle exchange, dispensing other drugs, and outreach services [38] . Harm reduction has been a controversial issue as compared to abstinencebased philosophies [39, 40] . Harm reduction seems to encourage tolerance of social phenomena that are undesirable and hazardous and that may result in social turpitude. Instead, abstinence is considered to be the proper way to address drug problems [39] . In the United States, law and policy restrict the use of federal funds in supporting needle and injection equipment distribution projects. However, many studies refute the concern that access to sterile syringes is an endorsement of IDU and is likely to result in increases in injection and initiation of injection [41, 42] . Harm reduction projects in China are in the pilot phases. Some scholars and health officials still have similar concerns as in some Western countries. They believe that needle exchange services may send a wrong signal of encouraging drug abuse to drug users and the public, and they consider methadone substitution unethical because it uses one drug to replace another drug [43] . As drug use and HIV/AIDS spread rapidly across the country, it is urgent to find supporting domestic evidence that harm reduction will reduce HIV transmission by evaluating harm reduction projects and ultimately scaling up harm reduction efforts.