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Social Networks and the Hepatitis C Virus

Hepatitis C continues to be a major health problem in Australia and is a leading cause of liver failure and liver cancer.

In Australia, as well as in other high income countries the vast majority of HCV infections occur in people who inject drugs.

At the time this work was undertaken there were an estimated 10,000 new HCV infections annually in Australia, with over 85% thought to be due to injecting drug use.

Prevention of HCV transmission is vital to halt an ever-increasing burden of HCV-attributable disease: to do so, we must understand the drivers of transmission and the associated behavioural or immunological factors.

Although some individual-level risk factors for HCV are well known (such as sharing used needles), the population-level phenomena driving HCV transmission are not as well understood.

We had previously shown that hepatitis C risk is dependent on the hepatitis C status of the people within injecting network – more so than on injecting partner numbers or needle-sharing behaviour.


This work involves over 400 people who contributed blood samples and detailed behavioural and social network data to the Networks study, with over 240 providing multiple blood sample at each encounters (some up to 15) during the four years of data collection.

This longitudinal design of this work was a major strength, because infections can be observed as they occur and their causes become easier to pinpoint.

A major outcome of the study was finding that people who had cleared an HCV infection were more likely to acquire a second virus than people who had never been infected.

Another key finding was the network structure played a role in how quickly infection spread with the community.

A key outcome of this work was using the network structure to provide treatment - using a "treat your friends approach" was beneficial in reducing hepatitis C prevalence and incidence (likely by reducing reinfection risk).

The results of this work informed national and global guidelines on approaches to hepatitis C treatment and elimination efforts.

Square Margaret Hellard 210X210

Professor Margaret Hellard AM

Contact Professor Margaret Hellard AM for more information on this project.


Partners +

  • Pip Pattson, Psychology, University of Melbourne
  • Galina Daraganova, Psychology, University of Melbourne
  • Peter Vickerman, London School of Hygiene and Tropical Medicine, UK
  • Jason Grebely, University of New South Wales
  • Emma McBryde, Queensland University of Technology
  • Cameron Hall, Queensland University of Technology
  • Scott Bowden, Victorian Infectious Diseases Reference Laboratory
  • Mandvi Bharadwaj, Immunology, University of Melbourne