Low risk of variant Creutzfeldt-Jakob disease transmission from blood transfusions in Aotearoa New Zealand suggests donor exclusion policies can be relaxed.

Aotearoa New Zealand currently excludes potential blood donors who lived in the United Kingdom (UK) for 6 months or more between 1980 and 1996. This action is due to the potential for variant Creutzfeldt-Jakob disease (vCJD) following blood transfusions from preclinical vCJD cases, who themselves mostly developed disease from the consumption of cattle with bovine spongiform encephalopathy (BSE) during this period, or from those incubating the misfolded prion proteins that cause disease. This donor exclusion policy led to 10% of New Zealand's active blood donors in 2000 being excluded, and it remains today despite periodic shortages of some blood products. Globally there have been 232 vCJD cases recorded-178 in the UK-with no new cases since 2019 and the peak numbers 23 years ago in 2000. Only three confirmed cases have been linked to blood transfusion. Here, we aimed to estimate the annual risk of vCJD from blood transfusion in New Zealand after restriction removal. We used UK case numbers, population estimates, and donor and recipient transfusion numbers to calculate the risk to the New Zealand public. We calculated the risk, based on approximately 131,000 transfusions a year and accounting for multiple transfusions, might lead to 0.005 cases annually, or approximately one in one billion nationally, and comparable to recent one in 1.45 billion estimates for Australia. Our analyses suggests that relaxing current blood donation restrictions, like Ireland and Australia's recent policy changes, would lead to an extremely low risk of vCJD transfusion-transmission in New Zealand. This policy change would help increase the supply of blood products for multiple medical needs.