HPR volume 16 issues 9 and 10: news (29 September 2022)
Updated 30 December 2022
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Annual review from NHS Blood and Transplant and UKHSA Epidemiology Unit
The latest annual review of the joint NHS Blood and Transplant (NHSBT) and UK Health Security Agency (UKHSA) Epidemiology Unit has been published on the NHSBT website. The Unit monitors infections in blood, tissue and organ donors, and in transfusion recipients, collates epidemiological data on bloodborne infections among donors and assesses associated risk of transmission through transfusion and transplant.
The Unit’s latest annual report comprises an 18-page overview (with infographics) of several streams of the Unit’s work including blood donor demographics; monitoring of infections in blood donations, including HEV; transfusion transmitted infections; infections identified post-transfusion and those identified by lookback; tissue and cord donations; and horizon scanning.
A section is devoted to the new policy FAIR (For the Assessment of Individualised Risk), implemented across the UK from June 2021, whereby a more equitable approach to the way blood donor selection takes account of sexual behaviours of prospective donors. Under FAIR, pre-donation questions relating to sex between men were removed and all donors were asked the new FAIR questions about their recent sexual activities, irrespective of gender. Surveillance data six-months post implementation showed there was no impact on safety, however close monitoring continues. The pre-donation question regarding sex with a partner from HIV endemic areas was removed by the end of 2021 across the UK.
The joint NHSBT/UKHSA Epidemiology Unit was established in 1995 and comprises a small team of epidemiologists and public health specialists working with scientific and clinical colleagues across both NHSBT and UKHSA.
In 2021, blood donations increased to meet demand following a drop in 2020, with 1.7 million donations made across the UK. An improvement in ethnic diversity among the donors was seen with 11% of new donors of Black and Asian ethnicities compared to 7.5% in 2020. More of the rarest blood type transfusion components are needed for multi-transfused patients, such as those with Sickle Cell Disease, which are far more prevalent in donors of Black African, Black Caribbean and Asian ethnicities. Research and marketing continue to target and encourage these communities to become donors.
The overall number of blood donations with confirmed markers of infection remained low across the UK with 280 (or one in 6,000) positive for markers of either hepatitis B virus, hepatitis C virus, HIV, HTLV or treponemal antibody (syphilis). The donations were discarded, and the donors deferred from donating and referred for follow up care. These positive donors generally had past prevalent infections that were not a risk to the safety of the supply. Chronic HBV and past syphilis in new donors continued at the raised level initially seen before the implementation of the new FAIR donor selection policy. In 2021, there were only 3 recent viral infections identified (2 hepatis B and one HIV), compared to 5 in 2020. The very low number detected meant that the chance of not detecting a virus in a donation that could enter the supply remained extremely low at less than an estimated one in 1,000,000. There were no proven transfusion-transmitted infections reported during 2021 although one possible transmission of occult hepatitis B was identified. During 2022 the UK blood services introduced hepatitis B anti-core screening to reduce the risk of non-detection of occult hepatitis B infections.
A further 398 donations tested positive for markers of hepatitis E virus. These donations were also discarded but the donors were able to return to donate after 6 months for whole blood donors or sooner for apheresis donors. Screening for HEV in the UK was first introduced for some donations in 2016 and extended to all donations from April 2017. Hundreds of HEV RNA positive donations are identified and removed from the supply each year. There have been 3 reported and investigated HEV transfusion transmissions in screened donations; one confirmed transmission from 2018, and one confirmed and one probable from 2019. The 2 confirmed incidents were identified via lookback investigations in repeat donors. The Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) has set up a working group to re-examine the effectiveness of current HEV screening of blood and platelet (apheresis) donors and to advise on whether it is sufficient to minimise transmission risk.
Human T-cell Lymphotropic Virus (HTLV) screening of blood donations has now been in place for 20 years, although since 2017 only donations from new donors and those used for certain products are tested. Throughout screening, rates of positive donations have been generally low, with few donors known to have seroconverted suggesting little recent transmission within this population. Transmission risk to recipients is likely to be negligible because of leucodepletion, however screening has clear public health benefits.
Living surgical bone donors are low in numbers and rarely have infections. In 2021, there were 365 tested for donation by NHSBT and no markers of viral or syphilis infections were detected however 2 were positive for malaria. A range of tissues are collected from deceased donors, a significant percentage being corneas. Among 1834 deceased tissue donors tested for donation, 2 donors had chronic hepatis B, 2 hepatis E, and one past syphilis, with rates if infection approximately three-fold higher than blood donors. In 2021, three hospitals in the London area collected cord blood from 92 pregnant donors, this was tested by NHSBT and none were found to be positive. Markers of infection are rarely identified in cord blood donors at the time of delivery as antenatal screening will usually detect HIV, hepatitis B or syphilis in these donors.
In collaboration with UKHSA, the Unit continues to monitor the risk of emerging infections – including most recently, monkeypox – to the blood supply using a range of national and international evidence sources. Changes made to travel-related donor selection criteria include updates to tropical virus and malaria risk areas. No evidence for coronavirus (COVID-19) transmission through blood transfusion has been identified to date, however, surveillance of COVID-19 risk to blood supply is ongoing.
The full report is available on the NHSBT website.
A detailed summary of data from all the Unit’s surveillance schemes is available on request to: epidemiology@nhsbt.nhs.uk.
Infection reports in this issue
Sexually transmitted Shigella spp. in England – data up to Quarter 2, 2022)
Laboratory confirmed cases of invasive meningococcal infection in England: January to March 2022
Group A streptococcal infections: update on seasonal activity in England, 2021 to 2022
Laboratory confirmed cases of measles, rubella and mumps in England: April to June 2022
Acquired carbapenemase-producing Gram-negative bacteria in England: October 2020 to June 2022