Blood donations in the UK have been screened for HIV antibodies since October 1985. The safety of blood transfusions was further reinforced with the introduction of fourth-generation tests (since 2001, except in Northern Ireland) and of RNA testing (in some regions from 2002, and in all parts of the UK from 2007).1
Nonetheless, there is still the possibility of a donation
being made during the window period between being infected and the test showing
a positive result. For this reason, people who may be at a higher risk of having
an infection are asked not to make blood donations.
relate to behaviours at any time in a person’s life. For example, people who
have sold sex and people who have injected drugs are requested never to donate
blood (even if they used drugs just once). Other restrictions apply to
behaviours in the past twelve months – for example, men who have had sex with
men, people who have had sex in a high-prevalence country and people whose partner
has had sex in a high-prevalence country. Further restrictions apply to
behaviours in the past four months (for example, tattooing and acupuncture).
Since 1985, there have been two incidents in which HIV-infected blood entered the UK blood supply, leading to a total of four infections. Both incidents would probably have been avoided if HIV RNA testing was being used at the time (as is now standard practice).
In 1997, one donation led to three infections.2 When one of the recipients had symptoms of HIV infection, stored samples of the donated blood were retested. This confirmed that the blood was negative for antibodies (the screening test that had been used), but it was found that the blood was positive for RNA. It is thought that the donor was infected shortly before donating.
In 2003, a blood donor tested positive for HIV antibodies.3 As this was not the first time the individual had donated blood, their previous donations were identified and re-analysed. A sample from a donation in 2002 was found to be negative for antibodies but positive for RNA, and the recipients of this sample included one person who tested positive for HIV and had had seroconversion symptoms three weeks after the transfusion.
During 2007, 24 blood donations were identified as HIV-positive during routine screening (a rate of 1 per 100,000). Given the window period, false negative results and errors in processing, there is still a very small possibility of infected blood not being detected. The Health Protection Agency estimates that this might be the case for 1 in each 5 million blood donations.1
Moreover, there have been incidents in 2000, 2002 and 2008 in which batches of infected blood have entered the American blood supply and led to infections, despite the use of HIV RNA screening. This demonstrates that there is still a window period on
the most sensitive tests (estimated to be nine days). Extremely recent
infection in the donors was suspected. In each case, phylogenetic analysis suggested
a link between the infections of the donors and recipients.4,5,6
Since 2003, there have been no new HIV diagnoses resulting from UK blood donations. However, each year between 20 and 40 new diagnoses have been attributed to infection from blood or tissue products acquired abroad. In around two-thirds of cases, the country where the blood donation or other procedure took place was in Africa. For example, in 2006, 26 diagnoses were attributed to blood donations in Africa, less than five to named countries in other parts of the world, and in seven cases the country was not reported. (Data provided to NAM by the Health Protection Agency, April 2009.)