Objective: To assess the role of polymerase chain reaction in defining infectiousness among people infected with hepatitis C virus. Design: Published studies of hepatitis C transmission were examined. Twenty nine studies with identified sources of hepatitis C infection who were tested for presence of hepatitis C RNA by polymerase chain reaction were reviewed, including studies of vertical transmission (n = 21), transmission after transplantation (n = 3), transfusion of blood components (n = 3), and needlestick exposure (n = 2). Subjects: All patients identified in studies. Results: A total of 2022 people who had been exposed to sources positive for antibody to hepatitis C were identified. Among 1148 people exposed to sources positive by polymerase chain reaction 148 cases of transmission occurred compared with no definite case among 874 people exposed to negative sources. Rates of transmission from positive sources were 6.2% for perinatal exposure, 6.1% after needlestick exposure, 78% after solid organ or bone marrow transplantation, and 83% after transfusion of blood components. Other factors influencing risk of vertical transmission were coinfection with HIV and level of hepatitis C viraemia. Conclusions: Negative results by polymerase chain reaction indicate an extremely low probability of transmission of hepatitis C from a person with antibody to hepatitis C.

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This new device allows spectacular dose reduction, consistent with adequate clinical information. Improvements of the prototype will lead to extension of potential indications and industrial development.