Back HCV Prevention Injection Drug Users Who Know They Have Hepatitis C Practice "Sero-Sharing"

Injection Drug Users Who Know They Have Hepatitis C Practice "Sero-Sharing"


People who inject drugs who know they are hepatitis C virus (HCV) positive are more likely to share syringes and injection equipment with others who are also infected, and less likely to do so with people who are HCV negative or unknown -- the equivalent of sexual "serosorting," according to a report in the December 15, 2013, Journal of Infectious Diseases.

Serosorting is a well-recognized and widely used strategy among gay men for reducing the risk of HIV transmission, by having sex only with partners of the same serostatus or making decisions about specific sexual activities or positions on that basis. People who inject drugs may employ similar strategies when making decisions about injection practices such as needle sharing.

Bryce Smith from the U.S. Centers for Disease Control and Prevention (CDC) and colleagues analyzed data from the 2009 National HIV Behavioral Surveillance System-Injection Drug Users to see whether serosorting -- considering HCV serostatus when deciding whether and with whom to share injection equipment -- was occurring among people who inject drugs.

The analysis included 9690 injection drug users in 20 major cities across the U.S. who were asked to report their own hepatitis C status and that of the person with whom they last shared injection equipment within the past 12 months. HCV testing of participants and partners was not done in this study.

Most participants (72%) were men, 47% were black, 22% were Hispanic/Latino, and 27% were white; the mean age was approximately 46 years. Nearly 60% were unemployed, 61% had ever been homeless, and 32% started injecting before age 18.


  • 75% of study participants said that they knew their HCV status.
  • 57% of participants who knew their status reported that they were HCV positive.
  • 47% reported sharing equipment with their last injecting partner.
  • 38% of these said they knew the HCV status of their last equipment-sharing partner.
  • Participants who knew their HCV status were more likely to know the status of their most recent injecting partner compared to those who did not know their own status:
  • People who knew they were HCV positive were about 4 times more likely to know their last partner's status (adjusted odds ratio [OR] 4.1);
  • People who knew they were HCV negative were more than twice as likely to know their last partner's status (adjusted OR 2.5).
  • Participants who reported being HCV positive were nearly 5 times more likely to share injection equipment with partners who were also HCV positive (adjusted OR 4.8).

Based on these findings, the study authors concluded, "People who inject drugs are more likely to share injection equipment with persons of concordant HCV status."

"Our analysis...points to the possibility that [people who inject drugs] are serosorting based on knowledge of their and their injecting partners’ HCV status," they added. "If accurate, the ability to increase [people who inject drugs'] awareness of their HCV status will have important consequences for public health and disease prevention, as it could be an influential element in a person’s decision to make health-promoting behavioral changes and their choice of medical treatment.

"Future research should include analyses of serosorting behavior based on actual versus perceived HCV status," they recommended. "[G]iven the unexplained differences in knowledge of serostatus by gender, race, educational attainment and homelessness, additional research should be conducted to examine these issues fully."

In an accompanying editorial, Arthur Kim from Harvard Medical School and Kimberly Page from the University of California at San Francisco noted that new outbreaks of hepatitis C in multiple areas of the U.S. have been tied to increasing rates of opiate use among young adults.

The study findings "imply that testing has been widely applied in this population and that status is shared among injecting groups," they continued. "What is not clear is whether testing is as widespread in nonurban settings, such as the 'exurban' areas where opiate use and HCV cases may be rising."

It is also unclear how HCV serostatus correlates with infectiousness -- unlike HIV, where it is well known that viral load increases the risk of transmission. During acute HCV infection there is a window period of about 6 weeks when the virus is present but antibodies are not yet detectable; conversely, some people clear HCV spontaneously or with treatment but remain HCV antibody positive -- and susceptible to reinfection.

"These complexities have the potential to result in incorrect perceptions or interpretations of HCV infectiousness," Kim and Page wrote. "Thus, serosorting is even less likely to be effective as a preventive strategy among [people who inject drugs] to avoid HCV than the parallel sexual behaviors observed among [men who have sex with men] to avoid HIV-1."

The study authors' suggestion that drug injectors' awareness of their HCV status will have important consequences for public health, they concluded, will be realized "only if testing is both accurate and comprehensive, then accompanied by counseling that is truly informative of those at risk of and with infection, and finally followed by linkage to treatment."



BD Smith, A Jewett, RD Burt, et al. "To Share or Not to Share?" Serosorting by Hepatitis C Status in the Sharing of Drug Injection Equipment Among NHBS-IDU2 Participants. Journal of Infectious Diseases 208(12):1934-1942. December 15, 2013.

AY Kim and K Page. Hepatitis C Virus Serosorting in People Who Inject Drugs: Sorting Out the Details. Journal of Infectious Diseases 208(12):1929-1931. December 15, 2013.