What is the most common virus transmitted by blood transfusion?

Hepatitis C is the Most Common Virus Transmitted by Blood Transfusion

The most common virus transmitted by blood transfusion is Hepatitis C (HCV). 1

Evidence Supporting HCV as the Most Common Transfusion-Transmitted Virus

Historically, HCV has been the predominant viral infection transmitted through blood transfusions:

• Before screening methods were implemented, HCV (previously known as non-A, non-B hepatitis) accounted for 90% of post-transfusion hepatitis cases 1
• In the 1960s, rates of post-transfusion hepatitis exceeded 20%, with the majority later identified as HCV 1
• Even after the move to all-volunteer blood donors in the mid-1970s, HCV still accounted for approximately 10% of transfusion-related infections 1
• Population-based surveillance demonstrated that non-A, non-B hepatitis (later identified as primarily HCV) accounted for 15%-20% of community-acquired viral hepatitis in the United States 1

Comparison with Other Transfusion-Transmitted Viruses

Hepatitis B (HBV)

• HBV transmission through transfusion became rare much earlier than HCV
• By the mid-1970s, improved screening and exclusive use of non-paid donors reduced post-transfusion hepatitis B to 0.3%-0.9% per transfusion recipient 1
• By the late 1980s, post-transfusion HBV had declined to approximately 1% of acute cases 1
• Current incidence of post-transfusion hepatitis B is estimated at around 0.002% per transfusion recipient 1

Hepatitis A

• Not typically considered a significant transfusion-transmitted virus
• Not mentioned in the guidelines as a major concern for blood transfusion safety 1

CMV (Cytomegalovirus)

• While CMV can be transmitted through blood transfusion, it is not highlighted in the guidelines as the predominant transfusion-transmitted virus 1
• Not mentioned as a major concern compared to HCV in transfusion medicine

Current Risk Status

While modern screening has dramatically reduced the risk of all transfusion-transmitted viruses:

• Since 1994, the risk for transfusion-transmitted HCV infection has become extremely low (0.001% per unit transfused) 1
• However, historically and in terms of overall disease burden, HCV remains the most significant transfusion-transmitted viral infection
• HCV is responsible for an estimated 8,000-10,000 deaths per year in the US, with 40% of chronic liver disease being HCV-related 1

Key Points About HCV Transmission

• HCV is transmitted primarily through large or repeated direct percutaneous exposures to blood 1
• Blood transfusion accounted for a substantial proportion of HCV infections acquired more than 10 years ago 1
• Currently, injecting-drug use accounts for 60% of HCV transmission in the United States 1
• The prevalence of HCV infection is highest among those with large or repeated direct percutaneous exposures to blood, including recipients of transfusions from HCV-positive donors 1

Therefore, based on the historical evidence and epidemiological data, Hepatitis C is the correct answer as the most common virus transmitted by blood transfusion.