[Injuries from needles contaminated with hepatitis C virus: how high is the risk of seroconversion for medical...

The risk of infection after injury with a needle contaminated with hepatitis C virus (HCV) is thought to be about 3%, but this assumption is mainly based on studies published in the 1990's, which were limited by small sample sizes and insensitive HCV-RNA assays. We therefore investigated needle injuries at the Hannover Medical School over a period of 6 years and performed a systematic review of the literature identifying 22 studies with a total of 6,956 injuries with HCV contaminated needles. Between 2000 and 2005, 1,431 occupational injuries were reported at our institution and two-thirds were needle injuries. Index patients were known to be HCV infected in 166 cases but there were no cases of HCV seroconversion during follow-up. Analysis of published data showed seroconversion rates of 0-10.3% with a mean of 0.75% (52/6,956). The risk of acute HCV infection was lower in Europe with 0.42% compared to Eastern Asia with 1.5% of cases where an HCV viremia was reported during follow-up. In summary, the risk of acquiring an HCV infection after a needlestick injury is lower than frequently reported. Worldwide differences in HCV seroconversion rates suggest that genetic factors might provide some level of natural resistance against HCV. Future studies should address not only the frequency of acute hepatitis but also factors associated with a higher risk of becoming HCV infected.