Helen Faddy

Climate change substantially threatens public health, including the blood supply chain, which is crucial for medical treatments such as surgeries, trauma care, and chronic disease management. Extreme weather events, vector-borne disease shifts, and temperature fluctuations can disrupt blood collection, testing, transport, and storage, threatening both the safety and sufficiency of blood products. Although studies have highlighted some connections between climate change, transfusion-transmissible infections, and blood safety, there remains a lack of comprehensive understanding of the climate effects on each supply chain stage. In this Personal View, we address the potential climate-driven challenges across the blood supply chain, from donor health to blood component stability, emphasising the importance of proactive measures. To protect the availability and safety of blood supplies in an evolving climate, further research and adaptive strategies are needed to build a resilient blood supply system that can withstand emerging climate-related disruptions.

Background and Objectives:
Nucleic acid amplification testing (NAT), in blood services context, is used for the detection of viral and parasite nucleic acids to reduce transfusion-transmitted infections. This project reviewed NAT for screening blood donations globally.

Materials and Methods:
A survey on NAT usage, developed by the International Society of Blood Transfusion Working Party on Transfusion-transmitted Infectious Diseases (ISBT WP-TTID), was distributed through ISBT WP-TTID members. Data were analysed using descriptive statistics.

Results:
Forty-three responses were received from 32 countries. Increased adoption of blood donation viral screening by NAT was observed over the past decade. NAT-positive donations were detected for all viruses tested in 2019 (proportion of donations positive by NAT were 0.0099% for human immunodeficiency virus [HIV], 0.0063% for hepatitis C virus [HCV], 0.0247% for hepatitis B virus [HBV], 0.0323% for hepatitis E virus [HEV], 0.0014% for West Nile virus [WNV] and 0.00005% for Zika virus [ZIKV]). Globally, over 3100 NAT-positive donations were identified as NAT yield or solely by NAT in 2019 and over 22,000 since the introduction of NAT, with HBV accounting for over half. NAT-positivity rate was higher in first-time donors for all viruses tested except WNV. During 2019, a small number of participants performed NAT for parasites (Trypanosoma cruzi, Babesia spp., Plasmodium spp.).

Conclusion:
This survey captures current use of blood donation NAT globally. There has been increased NAT usage over the last decade. It is clear that NAT contributes to improving blood transfusion safety globally; however, there is a need to overcome economic barriers for regions/countries not performing NAT.

Passive immunisation with normal human immunoglobulin (NHIG) is recommended as post-exposure prophylaxis (PEP) for higher-risk measles contacts where vaccination is contraindicated. However, the concentration of measles-specific antibodies in NHIG depends on antibody levels within pooled donor plasma. There are concerns that measles immunity in the Australian population may be declining over time and that blood donors’ levels will progressively decrease, impacting levels required to produce effective NHIG for measles PEP. A cross-sectional study of Australian plasmapheresis donors was performed using an age-stratified, random sample of recovered serum specimens, collected between October and November 2019 (n = 1199). Measles-specific IgG antibodies were quantified by ELISA (Enzygnost anti-measles virus IgG, Siemens), and negative and equivocal specimens (n = 149) also underwent plaque reduction neutralisation testing (PRNT). Mean antibody levels (optical density values) progressively decreased from older to younger birth cohorts, from 2.09 [±0.09, 95% CI] to 0.58 [±0.04, 95% CI] in donors born in 1940–1959 and 1990–2001, respectively (p < 0.0001). This study shows that mean measles-specific IgG levels are significantly lower in younger Australian donors. While current NHIG selection policies target older donors, as younger birth cohorts become an increasingly larger proportion of contributing donors, measles-specific antibody concentrations of NHIG will progressively reduce. We therefore recommend monitoring measles-specific antibody levels in future donors and NHIG products in Australia and other countries that eliminated measles before the birth of their youngest blood donors.

Arboviruses pose a significant global public health threat, with Ross River virus (RRV), Barmah Forest virus (BFV), and dengue virus (DENV) being among the most common and clinically significant in Australia. Some arboviruses, including those prevalent in Australia, have been reported to cause transfusion-transmitted infections. This study examined the spatiotemporal variation of these arboviruses and their potential impact on blood donation numbers across Australia. Using data from the Australian Department of Health on eight arboviruses from 2002 to 2017, we retrospectively assessed the distribution and clustering of incidence rates in space and time using Geographic Information System mapping and space–time scan statistics. Regression models were used to investigate how weather variables, their lag months, space, and time affect case and blood donation counts. The predictors’ importance varied with the spatial scale of analysis. Key predictors were average rainfall, minimum temperature, daily temperature variation, and relative humidity. Blood donation number was significantly associated with the incidence rate of all viruses and its interaction with local transmission of DENV, overall. This study, the first to cover eight clinically relevant arboviruses at a fine geographical level in Australia, identifies regions at risk for transmission and provides valuable insights for public health intervention.

Objectives: To estimate the prevalence of exposure to the causative agent of Q fever (Coxiella burnetii) and of current infections among blood donors in Australia. Design, setting: Cross-sectional study in metropolitan Sydney and Brisbane, and in non-metropolitan regions with high Q fever notification rates (Hunter New England in New South Wales; Toowoomba in Queensland). Participants: Blood donors attending Red Cross collection centres during October 2014 - June 2015 who provided sera and completed a questionnaire on Q fever vaccination status, diagnosis and knowledge, and exposure history. Main outcome measures: Age- and sex-standardised seroprevalence of phase II IgG antibodies to C. burnetii (indicating past exposure) and independent risk factors for seropositivity; presence of C. burnetii DNA (indicating current infection and risk of transmission by blood transfusion). Results: 2740 donors (94.5% response rate) completed the questionnaire and supplied sera for analysis. Crude antibody seroprevalence was 3.6%. Standardised seroprevalence was higher in non-metropolitan than metropolitan regions (NSW, 3.7% v 2.8%; Queensland, 4.9% v 1.6%; statistically significant only in Queensland). Independent predictors of antibody seropositivity were regular contact with sheep, cattle, or goats (adjusted odds ratio [aOR], 5.3; 95% CI, 2.1-14), abattoir work (aOR, 2.2; 95% CI, 1.2-3.9), and assisting at an animal birth (aOR, 2.1; 95% CI, 1.2-3.6). Having lived in a rural area but having only rare or no contact with sheep, cattle or goats was itself a significant risk factor (v never lived rurally: aOR, 2.5; 95% CI, 1.1-5.9). 40% of people in groups recommended for vaccination were aware of the vaccine; 10% of people in these groups had been vaccinated. C. burnetii DNA was not detected in 1681 non-metropolitan samples, suggesting that transmission by blood donation is unlikely. Conclusions: Given their exposure to multiple risk factors, vaccination against Q fever should be considered for all rural residents.

BACKGROUND: Emerging transfusion-transmissible pathogens, including arboviruses such as West Nile, Zika, dengue, and Ross River viruses, are potential threats to transfusion safety. The most prevalent arbovirus in humans in Australia is Ross River virus (RRV); however, prevalence varies substantially around the country. Modeling estimated a yearly risk of 8 to 11 potentially RRV-viremic fresh blood components nationwide. This study aimed to measure the occurrence of RRV viremia among donors who donated at Australian collection centers located in areas with significant RRV transmission during one peak season. STUDY DESIGN AND METHODS: Plasma samples were collected from donors (n= 7500) who donated at the selected collection centers during one peak season. Viral RNA was extracted from individual samples, and quantitative reverse transcription-polymerase chain reaction was performed. RESULTS: Regions with the highest rates of RRV transmission were not areas where donor centers were located. We did not detect RRV RNA among 7500 donations collected at the selected centers, resulting in a zero risk estimate with a one-sided 95% confidence interval of 0 to 1 in 2019 donations. CONCLUSION: Our results suggest that the yearly risk of collecting a RRV-infected blood donation in Australia is low and is at the lower range of previous risk modeling. The majority of Australian donor centers were not in areas known to be at the highest risk for RRV transmission, which was not taken into account in previous models based on notification data. Therefore, we believe that the risk of RRV transfusion transmission in Australia is acceptably low and appropriately managed through existing risk management, including donation restrictions and recall policies.