Transfusion-transmissible infection surveillance report

Transfusion-transmissible infections surveillance reports

In 2011, Lifeblood 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.
 
Lifeblood 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 2023 transfusion-transmissible infections in Australia surveillance report has now been published and the major findings and Lifeblood responses are as follows:
  
1. Supporting the effectiveness of donor education and selection, the prevalence of TTIs in 2022 is substantially lower among first-time blood donors (6 to 64 times) than in the general population in 2021/2022.  Over the 10 year period 2013-2022, all TTIs with the exception of hepatitis C virus (HCV), show a stable or declining trend. For HCV, a significant increasing trend was observed in the prevalence of first-time donors. Notably this was an increase in resolved infection (i.e. antibody positive only) and the total proportion of HCV RNA positive donations has declined from around 75% when NAT testing was introduced in 2000, to 29.7% in 2022.
 

2. Although representing 21.8% of the donor population, first‑time blood donors contributed to 85% of detected TTIs in Australia in 2022, a 7% increase as compared to the 79% observed in 2021.
 

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 generally understand what constitutes ‘risk behaviour’ for acquiring TTIs.
 

4. Infective exposure risk factors identified in blood donors with TTIs 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 in 2022 was 21%, mid-range of 15-25% observed in the last decade. The current rate highlights the importance of promoting donor education to ensure that 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 reported 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 a computer-assisted structured interview might lead to further improvement in the overall compliance rate. Lifeblood has since fully implemented an electronic donor questionnaire at all blood collection sites.
 

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 that Australia’s blood supply is among the safest worldwide in respect of TTIs for which testing is conducted. Despite this, there remains a minimal but real risk of TTIs that must be carefully considered before any transfusion.
 

8. Bacterial screening of 123,751 platelets donations identified 130 (0.11%) 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.

During 2022, there were no confirmed cases of transfusion-transmitted bacterial infection. Based on Lifeblood data from May 2008 – June 2023, the risk of transfusion-transmitted bacterial infection from a platelet transfusion is calculated to be 0.34 per 100,000. This compares favourably with Canadian Blood Services data indicating a rate of 0.41 per 100,000 platelet component.

  
9. In addition to established TTIs, emerging infectious diseases continue to demand vigilant surveillance and risk assessment. The landscape for emerging infections that represent a potential risk to blood safety changed considerably in 2020 due to travel restrictions significantly decreasing the risk. Notified case numbers for infections that have been predominately overseas acquired, such as dengue, hepatitis A, hepatitis E and malaria, decreased during the pandemic. However, by October 2023, notified case numbers for these four infections are near pre-COVID-19 levels. The ongoing risk from SARS-CoV-2, local dengue outbreaks, seasonal West Nile virus outbreaks in Europe, outbreaks of hepatitis A virus and Zika virus have been monitored during 2022-2023. In addition, during 2022 a local outbreak of Japanese encephalitis virus (JEV) and cases of mpox associated with a global mpox outbreak were monitored. Both outbreaks were assessed as a negligible risk to blood safety. Lifeblood also continues to monitor hepatitis A virus, hepatitis E virus and parvovirus B19 in Australia and a significant change in the risk profile has not occurred since the risk assessments were performed.
 

Lifeblood response to finding 1 - increasing trend in HCV prevalence in first-time donors

The increasing trend observed in HCV prevalence in first-time donors during the 2013-2022 period is likely to be the combined impact of two factors. Firstly, an increase in the number of prospective donors with ‘resolved’ HCV (HCV antibody positive/RNA negative) presenting to donate subsequent to successful treatment. These donors are not eligible, predominately because they test positive to the anti-HCV test resulting in discard. However, they attend because they are no longer infectious, so mistakenly think they are eligible. Secondly in late 2018, there was a change in the donor eligibility policy regarding injecting drug use with donors being eligible five years after last injecting drugs. Importantly these do not impact the blood safety risk as they will test positive and are not in the window period.
The 0.05% first‑time donor prevalence in 2022 is six times lower than the estimated ~0.3% living with chronic hepatitis C reported for HCV national surveillance data for 2022. However, these figures are not directly comparable as the majority of HCV‑positive donors represent past exposure.
 

Lifeblood response to finding 2 - Higher detection rate of transfusion-transmissible infections in first-time donors

First-time donor testing measures prevalent infection, whereas repeat donor testing measures incidence. Therefore, this is an expected finding. As documented above, an incident infection, where there is a risk of the donor being in the window period, is the predominant blood safety risk. However, donor selection also plays an important part in blood safety. Lifeblood focuses on education of all donors, particularly first-time donors, including providing a blood safety-based brochure translated into a number of languages highlighting the pivotal role of accuracy and honesty in answering the standard questionnaire. This is demonstrated to be effective in Finding 3.

In accordance with state and territory laws, there are penalties including fines and imprisonment for anyone providing false or misleading information.

Lifeblood considers the current proportion of first-time donations (7% in 2022) to be acceptable, noting that this proportion is at the lower range among internationally comparable blood services (7–25%). Importantly, achieving a lower proportion of first-time donors whilst maintaining fresh blood product sufficiency and expanding plasma donations is a positive outcome underpinned by an increasing annual average donation rate among repeat donors. Notably in July 2022, the variant Creutzfeldt‑Jakob disease geographical deferral for United Kingdom donors was removed. In the five month period, first‑time donors from this group accounted for 42% of all first‑time donor attendances, significantly contributing to the number of donations made during this period.

Lifeblood response to findings 5 and 6 - Non-compliance to screening questions

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 in 2012-2013 were lower than comparable overseas rates, Lifeblood remains committed to seeking further improvement.

One potential strategy to improve compliance is optimising the communication of the rationale underpinning deferral policies. Lifeblood continues to engage externally regarding initiatives to improve communication which includes optimising the use of social media, developing new and refining current education resources and translating education resources into languages other than English.

Furthermore, Lifeblood’s donor compliance 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. Lifeblood has now fully implemented an electronic donor questionnaire at all collection sites. Post-implementation results indicate that this initiative has improved both the donor experience, as well as reducing procedural (‘human’) errors, thus enhancing overall system safety. Its impact on the non-compliance rate is unknown but is predicted to lead to a lower rate.

Lifeblood response to finding 9 - Surveillance for emerging infections

Lifeblood maintains surveillance for emerging infections through liaison with government communicable disease control departments, CSL Behring, membership of international medical/infectious disease groups and active horizon scanning.

Potential threats are regularly reviewed by Lifeblood Donor and Product Safety Committee and Clinical, Quality and Research Governance 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.

Lifeblood has a comprehensive epidemic management plan - which was activated in response to SARS-CoV-2 in early 2020. Based on the epidemiology of known coronaviruses (SARS and MERS-CoV), the risk of transfusion transmission was assessed as low when the virus first emerged. The cumulative data, including over 770 million reported cases worldwide (at August 2023) without a reported case of transfusion transmission, supports that the risk is extremely low and currently ‘theoretical’.

Other notable applications of the epidemic management plan included novel outbreaks of JEV and mpox occurring in 2022. These were both subject to formal risk assessment and deemed as negligible risks to blood safety. Lifeblood also continues to monitor hepatitis A virus, hepatitis E virus and parvovirus B19 in Australia and a significant change in the risk profile has not occurred since the risk assessments were performed.