Transfusion-transmissible infections surveillance reports
In 2011, the Blood Service and the Kirby Institute published a comprehensive surveillance report for transfusion-transmissible infections (TTIs) - Safe blood – a focus on education, epidemiology and testing. This report analysed surveillance data for the period 2005–2010 and was the preface to planned annual TTI surveillance reports, with the first annual report being published the following year in 2012.
The Blood Service regularly reviews and updates the donor interview and selection process, taking into consideration local and overseas research studies, international best practice, literature reviews and analysis of surveillance data such as that included in this report.
The 2017 transfusion-transmissible infections in Australia surveillance report has now been published and the major findings and Blood Service responses are as follows:
1. Supporting the effectiveness of donor education and selection, the prevalence of transfusion‑transmissible infections is substantially lower among first‑time blood donors (15 to 102 times) than in the general population in 2016 and shows a stable or declining trend over the period 2007-2016.
2. The prevalence of transfusion‑transmissible infections among first‑time donations was much higher than the prevalence among all donations, highlighting the importance of promoting donor education of potential new donors and ensuring first‑time donors read the pre‑donation information and understand the importance of ‘self‑deferral’.
The Blood Service focuses on education of all donors, particularly first- time donors, including providing a specific blood safety brochure highlighting the pivotal role of accuracy and honesty in answering the standard questionnaire.
In accordance with state and territory laws, there are penalties including fines and imprisonment for anyone providing false or misleading information.
While every effort is made to maximise donor retention, there is a fundamental requirement for continuing recruitment of new donors: firstly, to replace existing donors who can no longer donate (e.g. due to age and/or medical ineligibility) and secondly, to meet the growing demand for some blood products.
The Blood Service considers the current proportion of first-time donations (7% in 2016) to be acceptable, noting that this proportion is in the lower range among internationally comparable blood services (7–25%).
3. The incidence of newly acquired infection measured by the rate of incident donors is also much lower than results from specific at‑risk populations in Australia. This supports the general effectiveness of the donor questionnaire and specifically that repeat donors understand what constitutes ‘risk behaviour’ for acquiring transfusion‑transmissible infections.
4. Infective risk factors identified in blood donors with transfusion‑transmissible infections closely parallel those for the general population with no ‘unique’ risk factors identified to date among blood donors.
5. The non‑compliance rate among TTI-positive donors improved from 25% in 2014 (the highest recorded) to 17% in 2015 then rose slightly to 19% in 2016. The current rate highlights the importance of promoting donor education to ensure that the potential donors understand the importance of ‘self‑deferral’ to reduce the risk of collecting blood from a potentially infected donor whose infection may not be detected by testing.
6. While non‑compliance among positive donors has been routinely monitored since 2000, the rate among TTI test‑negative donors is more difficult to track.
Results from a large national survey conducted in 2012-2013 showed a comparatively low rate of non-compliance (in the range 0.05 to 0.29%) among TTI test-negative donors for several sexual activity-based donor deferrals. The study included a multivariate analysis of factors influencing non-compliance, which suggested that the use of an audio computer-assisted structured interview (ACASI) might lead to further improvement in the overall compliance rate.
The Blood Service has commenced a strategic project to assess the operational feasibility of implementing ACASI nationally. Regulatory approval for any selected system would be required before implementation.
Non-compliance to screening questions remains an ongoing concern despite existing donor education initiatives targeting the importance of complete accuracy and honesty in answering the donor questionnaire.
As noted, it is pleasing that the results of the national survey showed a comparatively low rate of non-compliance (in the range 0.05 to 0.29%) among TTI test-negative donors for several sexual activity-based donor deferrals.
While it is reassuring that Australian rates are lower than comparable overseas rates, the Blood Service remains committed to seeking further improvement.
One potential strategy to improve compliance is optimising the communication of the rationale underpinning deferral policies. The Blood Service continues to take advice from an expert advisory panel regarding initiatives to improve communication. Recommendations include optimising the use of social media, developing new education resources and refining current education resources.
Furthermore, the study identified a correlation with non-compliance and concerns over ‘privacy’ of disclosure, which might be partially alleviated by the use of a ‘computer-based’ donor questionnaire. The Blood Service has initiated a comprehensive project to improve the donor assessment process including investigating the feasibility of using a ‘computer-based’ donor questionnaire for all donation types. Currently this is being trialled in plasma-only pilot sites. Its universal implementation is dependent on a successful validation and risk assessment prior to implementation.
7. The estimated residual risk of transmission for HIV, HCV, HBV, HTLV and syphilis in Australia is very low – less than one in one million per unit transfused. This supports the claim that Australia’s blood supply is among the safest worldwide in respect of transfusion‑transmissible infections for which testing is conducted. Despite this, there remains a minimal but real risk of transfusion‑transmissible infections that must be carefully considered before any transfusion.
8. Bacterial screening of 120 941 platelets identified 151 (0.12%) as confirmed positive. The majority of organisms identified were slow‑growing anaerobic skin flora not usually associated with post‑transfusion septic reactions. However, a minority of platelets grew clinically significant organisms that were likely to have been due to transient or occult bacteraemia in the donor and could have led to potentially serious septic transfusion reactions in the recipient. Septic transfusion reactions in two recipients of platelets from a single donor occurred in 2016; both platelets were negative on bacterial contamination screening.
Bacterial testing of platelets is one of a number of complementary strategies implemented by the Blood Service to reduce the risk of transfusion transmitted bacterial infection.
While the Blood Service rate of reported bacterial sepsis has remained very low and generally below comparable international figures, rare cases occur, highlighting the ongoing risk to blood recipients.
Cases of bacterial sepsis associated with platelet transfusions are rare, with the two cases in 2016 being only the fourth and fifth cases of transfusion-transmitted bacterial infection associated with platelets issued by the Blood Service since the introduction of bacterial screening in 2008. The rate of transfusion-transmitted bacterial infection associated with platelets issued by the Blood Service since 2008 is approximately 1 in 332 000, which compares favourably with overseas data where the reported rate in one large US study was approximately 1 in 107 000.
9. In addition to established transfusion‑transmissible infections, emerging infectious diseases continue to demand vigilant surveillance and risk assessment. Along with the ongoing risk from local dengue outbreaks and seasonal WNV outbreaks in Europe, outbreaks of Ebola virus and Zika virus have also been closely monitored during 2016‑2017.
The Blood Service maintains surveillance for emerging infections through close liaison with government communicable disease control units, CSL Behring, membership of international medical/infectious disease groups and active horizon scanning.
Potential threats are regularly reviewed by the Blood Service Donor and Product Safety Committee and Clinical Governance and Research Committee, and risk assessment performed in the event that a threat is identified as a clear and present threat to the safety of the blood supply. Where appropriate, this will be performed in collaboration with CSL Behring (in their capacity as national plasma fractionator) and the Therapeutic Goods Administration.