Since the theoretical risk of variant Creutzfeldt-Jakob Disease (vCJD) transmission through blood was first identified as a possibility in 1996, a series of precautionary measures have been implemented to protect the blood supply and products made by fractionating plasma, including:
Applicable to all blood/blood products
From December 1997, blood components, plasma products or tissues obtained from any individual who later develops vCJD, have been withdrawn/recalled to prevent their use;
From October 1999, white blood cells (which may carry a risk of transmitting vCJD) have been reduced in all blood used for transfusion, a process known as leucodepletion or leucoreduction;
Following the report of the first possible case of transmission of vCJD by blood transfusion in December 2003, individuals who had themselves received a transfusion of blood components since January 1980 were excluded from donating blood. This took effect from April 2004;
In July 2004, this exclusion criterion for blood donation was extended to include two new groups, who had received transfusions of blood components since 1980:
Previously transfused platelet donors,
Donors who were unsure if they had previously had a blood transfusion. This now applies to donors who have been transfused anywhere in the world;
In July 2005, the Department announced further precautionary measures for around 100 individuals who donated blood to three people who later developed vCJD. The notified people have been asked not to donate blood, tissues or organs and to inform health care professionals so extra precautions can be taken when they have surgery or other invasive procedures; and
In November 2005, the Department announced an extension of the July 2005 notification exercise. A further 50 people who had received blood from some of the 100 or so donors notified since July 2005 were traced and notified of their potential exposure to vCJD, and asked to take similar precautions.
Plasma
Since 1999, plasma for the manufacture of fractionated plasma products, such as clotting factors, has been obtained from non-UK sources;
Since 2004, fresh frozen plasma for treating babies and young children born on or after 1 January 1996 has been obtained from the USA;
Fresh frozen plasma for treating babies and young children born on or after 1 January 1996 has been obtained from the USA, and from July 2005 its use was extended to all children up to the age of 16;
The national health service has been instructed to purchase imported solvent detergent-treated pooled plasma for adult patients with thrombotic thrombocytopenic purpura; and
Synthetic (recombinant) clotting factor for treatment of haemophilia has been provided to the under-16s since 1998 and for all patients for whom it is suitable since 2005.
Platelets
To reduce donor exposure, the Advisory Committee on the Safety of Blood, Tissues and Organs in 2009 reiterated its predecessor committee's advice on increasing the percentage of platelets collected by apheresis to at least 80 per cent.
Cryoprecipitate (a special cold-treated plasma preparation)
Cryoprecipitate produced from methylene blue treated-plasma imported from the USA is being implemented for children up to the age of 16. The Advisory Committee on the Safety of Blood, Tissues and Organs is reviewing use of cryoprecipitate in older patients.
All of these recommendations were recommended or endorsed by the Advisory Committee on the Safety of Blood, Tissues and Organs (which first met in January 2008), or its predecessor committees.
Because of the apparently lengthy incubation period of vCJD and the small number of clinical cases observed to date, it is not possible to make a definitive assessment of the contribution each measure makes to the overall risk reduction.