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U.S. Department of Health and Human Services

Vaccines, Blood & Biologics

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Potential Variant Creutzfeldt-Jakob Disease (vCJD) Risk From Investigational Factor Eleven (pdFXI) From Donors in the United Kingdom: Summary Information, Key Points

Summary Information

Key Points:

  • In recent years, questions have been raised concerning the risk from variant Creutzfeldt-Jakob disease (vCJD), a rare but fatal brain infection, in patients who received plasma-derived investigational Factor Eleven (pdFXI) made from plasma obtained in the United Kingdom (UK) where vCJD has occurred.
  • Approximately 50 individuals in the US, between 1989 and 2000, received pdFXI made using plasma from donors in the UK. This product was used to prevent or treat bleeding due to a rare problem, a deficiency of FXI.
  • The US Public Health Service (PHS) believes that the risk of vCJD is likely to be small based on a number of considerations. We used a computer model to help determine the risk but we recognize that many unknowns prevent us from accurately determining the risk. The model raised the possibility that those who received this pdFXI product could potentially be at significant risk due to the possibility that a UK blood donor unknowingly carried vCJD at the time of donation. However, we believe the risk is small based on additional considerations. To date we are not aware of any cases of vCJD having been reported worldwide in patients with hemophilia or other blood clotting disorders, including pdFXI deficiency, who have received large amounts of plasma-derived products manufactured from UK plasma. This includes patients who received these products over a long period of time.
  • Contacting a specialist in bleeding disorders, e.g. a healthcare provider specializing in hemophilia, and/or a Hemophilia Treatment Center is a good way to learn about any new information as it becomes available.

Additional Information:

  • Between December 2003 and April 2007, there have been four reports of people, all in the UK, who probably acquired the vCJD agent through red blood cell transfusions. This has increased concern about the potential transmission of vCJD by blood products, particularly those made from UK blood donors. None of the reported cases involved any plasma-derived product, including pdFXI.
  • However, because of the finding that red blood cells can transmit vCJD, FDA used a computer model to conduct a risk assessment to try to estimate the possible risk that might occur from the UK investigational pdFXI.
  • The actual risk of acquiring vCJD is unknown and is likely to be small. Because so much is unknown about vCJD and its prevalence, the risk assessment performed by FDA has a lot of uncertainty, making it impossible to precisely estimate the risk of vCJD in general, or the actual risk to individual FXI deficient patients. There is no test yet available to detect vCJD in healthy donors or recipients. The US Public Health Service believes the risk of vCJD is likely to be small. There have been no reports of vCJD in patients using any plasma-derived blood product in the UK or anywhere else in the world.
  • At this time, PHS does not believe there is a need for UK pdFXI recipients to inform their surgeons or dentists about the recipient’s potential exposure to vCJD. Also, there is no recommendation for surgeons and dentists to take any special precautions based on such potential exposures. This belief is based on the very large degree of uncertainty in the FDA risk assessment and the lack of known cases of vCJD transmitted by plasma-derived clotting factor products in the UK, where risk is considered greatest, or anywhere else in the world. Also, relatively few patients were exposed to the pdFXI product in the US compared to the number of recipients of plasma-derived clotting factors, of which pdFXI is only one of many, in the UK.
  • vCJD originally came from a disease in cattle called “mad cow disease” or BSE (bovine spongiform encephalopathy). Transmission of the BSE agent to humans, leading to vCJD, is believed to occur primarily from eating beef and beef products contaminated with the BSE agent. Both BSE and vCJD are invariably fatal brain diseases with incubation periods typically measured in years.
  • From 1995 through April 2007, 202 individuals with vCJD were reported worldwide, with 165 in the United Kingdom (UK), and three in the United States. Two of the individuals in the United States had lived in the UK from 1980-1996 during a key exposure period to the BSE agent. The third US individual with vCJD most likely acquired the infection in Saudi Arabia. The reported incidence of vCJD in the UK, based on disease onset, peaked in 1999 and has been declining thereafter. In the UK, where most cases of vCJD have occurred, the current risk of acquiring vCJD from eating beef and beef products appears to be negligible.
  • More information about vCJD is available on these government websites:
  • Information also may be obtained from these non-government sources:
    • Committee of Ten Thousand
    • Hemophilia Federation of America
    • National Hemophilia Foundation and/or HANDI
    • World Federation of Hemophilia