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UK Blood Services joint statement on blood safety - August 2011

In the UK there are four Blood Services which operate well established nationally managed blood collection programmes of non-remunerated voluntary blood donation. These Blood Services, including NHS Blood and Transplant, supply blood to hospitals for transfusion into patients and in doing so have a clear legal and ethical requirement to strive to maintain an extremely high level of blood safety.

Almost every medical treatment including blood transfusion is associated with some risk. For this reason doctors need to consider the need for any blood transfusion very carefully with their patients. The risks of viral transmission by blood transfusion in the UK are exceedingly low: the last documented case of any virus transmission was in 2005. Bacterial contamination of blood components occurs at a very low rate, and recent risk reduction measures and the introduction of bacterial screening of platelets have further minimised the risk of this occurring. Last year, according to the SHOT (Serious Hazards of Transfusion) Annual Report 2010 was the first year in which there have been no confirmed cases of transfusion-transmitted infection, from any source including bacterial contamination. http://www.shotuk.org/shot-reports/report-and-summary-2010-2/

Donor selection criteria, stringent testing of blood donations and advances in technology mean that the UK blood supply is as safe as it reasonably can be.

The UK Blood Services are advised by a specialist committee, the Standing Advisory Committee on Transfusion Transmitted Infection (SACTTI), which reports to the United Kingdom Blood Transfusion Services/Health Protection Agency Joint Professional Advisory Committee (JPAC). Members of SACTTI are experts in the field of blood transfusion and in transfusion-transmitted infection, and include representatives from the Health Protection Agency (HPA), academic virology, bacteriology and parasitology and epidemiologists. The members of SACTTI, through well-established international connections with other blood services and infectious disease surveillance support by the Joint NHS Blood and Transplant/Health Protection Agency Epidemiology Unit, are alerted to outbreaks of infection and emerging infections outside the UK. SACTTI produces risk assessments which are considered by JPAC, and on which advice is issued to UK Blood Services.

Additionally the UK Government receives expert advice from the Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) on the most appropriate ways to ensure the safety of blood, cells, tissues and organs for transfusion / transplantation. SaBTO and the National Expert Panel on New and Emerging Infections (NEPNEI), monitor developments, both nationally and internationally, in conjunction with the UK Blood Services and the Health Protection Agency. All risk assessments are regularly reviewed, and if new evidence comes to light which means that risk assessments need to be amended, then this is done.

Sabto: http://www.dh.gov.uk/ab/SaBTO/index.htm
NEPNEI: http://www.dh.gov.uk/ab/NEPNEI/DH_096088

For more information on blood safety measures see the sections below:

1. Blood donor selection
Potential blood donors must be aged between 17 and 66 if donating for the first time. Following a change to the guidelines in December 2009, there is no longer an upper age limit for existing donors.

Every time a person volunteers to give blood they complete a donor health check questionnaire which is designed to determine whether giving blood could harm the donor's health, and whether they could be at an increased risk of infections which can be transmitted to patients through donated blood. The donor health check is a fundamental step in ensuring the safest possible blood for patients. This relies on donors supplying accurate and honest information.

If a donor answers 'yes' to a question which suggests they could be at higher risk of transmissible infections, they are asked not to donate, either for a fixed period or permanently. For example, anyone who had injected illegal or non-prescribed drugs or has ever tested positive for HIV is deferred for life. Anyone who has had sex with someone who has injected drugs, would be deferred for a fixed period to ensure that any infection they may have contracted through this behaviour would be detected by screening tests on donated blood.

For more information on blood donor selection criteria click here: http://www.transfusionguidelines.org.uk/index.aspx

2. Testing
All blood donations are tested on every occasion for evidence of infection with Human Immunodeficiency Virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), Human T-cell Lymphotropic Virus (HTLV), and syphilis. Sensitive tests are used which have been assessed as suitable for screening blood donors, a low risk population. In addition, donors who may been exposed to certain infections found outside the UK, but which are transmissible by blood transfusion (malaria and Trypanosoma cruzi -Chagas' disease) undergo specific testing before their blood is released for use. Tests for Cytomegalovirus (CMV) are also carried out on a number of donations to meet clinical needs for patients with depressed immunity.

The tests used are now extremely sensitive. However, there is a period just after becoming infected when a donor's blood could test negative yet still pass on the infection to the recipient- this is known as the window period and is one reason why it is so important that a donor is accurate in reporting infection risks e.g. travel.
If a newly detected acute infection is reported in a repeat blood donor, it is critical to ensure that the previous donation was not infectious and went undetected because it was made during the window period. Therefore a sample from every donation is archived and can be retrieved and retested. In addition a look-back investigation may be carried out on recipients of this previous donation. Lookback is used to identify transfusion transmitted-infections in recipients of previous donations. A recent paper published in TRANSFUSION http://onlinelibrary.wiley.com/doi/10.1111/j.1537-2995.2010.02996.x/abstract (Byrne et al., 2011) reported on the outcome of retrospective lookback investigations into previous donations from HIV positive blood donors in England and Wales. The yield of lookback was low with one positive transmission identified over a thirteen year period. This case predated the introduction of extra tests for viruses called Nucleic acid Amplification Technology screening. No cases have been reported since this was introduced. The study demonstrates the improved blood safety with current donation screening tests and the low risk of HIV transmission through blood transfusion in the UK.

3. Prevention of bacterial contamination
To reduce the risk of bacterial contamination, the blood donor's arm is swabbed with a disinfectant solution prior to venepuncture and the first small portion of a blood donation (most likely to contain bacteria from the donor's skin ) is diverted into a separate pouch and used for blood grouping and other essential laboratory tests on the donation. Both these measures contribute significantly to reducing the risk of transfusion transmitted infections. However, platelets are stored at 22°C, which makes them more susceptible to bacterial growth.
All of the UK blood services now screen platelets for the presence of bacteria. This is an additional risk reduction method and also enables the shelf life of platelets to be extended to 7 days.

4. vCJD
A number of safety measures are in place to reduce the risk of transmission of vCJD as there is no specific test available for screening of donors. These include lifetime deferral from donation by people who have been advised they may be at increased risk from vCJD; anyone who has had a blood transfusion; leucodepletion (removal of white blood cells) of all donated blood; the use of non-UK plasma for production of plasma products such as clotting factors; and importation of fresh frozen plasma for treatment of children under 16.

There have been only three clinical cases of vCJD definitely attributed to blood transfusion, where a donor later developed vCJD. These cases were associated with blood transfusions given in the years 1996 and 1997. A further case of transmission of vCJD infection, without development of clinical vCJD, was associated with a transfusion in 1999. There are a further four clinical cases of vCJD which might be associated with blood transfusion, but where none of the donors has developed clinical vCJD. The latest of these cases was transfused in 2002.

For more information on vCJD and prevention measures see the JPAC website: http://www.transfusionguidelines.org.uk/index.aspx?Publication=DL&Section=12&pageid=794