An Australian rule banning many former UK residents from giving blood over fears they could spread variant Creutzfeldt-Jakob disease (vCJD) was recently lifted. The lifting of this ban means an estimated 18,000 additional people living in Australia are now eligible to donate blood. Prof Iain Gosbell is the Medical Director of Donor and Product Safety at Australian Red Cross Lifeblood. He explains the change was made following a review into the risk modelling of people who may have been exposed to the disease.

“Since December 2000, people who lived in the UK for over six months between 1980 and 1996 have been unable to donate blood in Australia. This rule was introduced due to a UK outbreak of vCJD, often known as ‘mad cow disease’, a fatal neurological disease that can incubate undetected in a person for many years. There is now strong scientific evidence that the agent responsible for the outbreak of bovine spongiform encephalopathy (BSE) in cows, is the same agent responsible for the outbreak of vCJD in humans,” said Prof Gosbell.

BSE is a progressive neurological disorder of cattle which was present in the UK in the 1980s and 1990s and was caused by feeding cattle to cattle. BSE passed over to humans in 1995 and was followed by a spate of cases before a connection was made to humans eating beef.

“When vCJD emerged in the UK, Australia introduced a precautionary deferral, in parallel with blood services throughout the world. Anyone that had spent any longer than six months in the UK between 1980 and 1996 got a permanent deferral. At that time, we didn’t know whether this devastating new disease would transmit by blood and there were more and more cases emerging, not only in the UK, but also in other countries in Europe.

“After we introduced the deferral, we received reports that there had been transfusion transmitted cases – at least three in the UK – showing that blood services were right to introduce this precautionary measure. Modelling at the time showed there was potential for a huge epidemic of human cases but, rather fortuitously, the numbers remained small – 233 reported cases, 178 of which were in the UK. Since the deferrals were brought in, there were no other cases of transfusion transmission of vCJD.

Cases of vCJD peaked in the UK in 2000 and declined rapidly thereafter. The last known case in the UK was detected after the patient had died in 2016.

“Since vCJD has all but disappeared, we thought it was time to consider whether this geographic deferral is still needed. We enlisted the assistance of statistics and epidemiologic colleagues at the Kirby institute at the University of NSW, along with a colleague at the U.S. Food and Drug Administration (FDA) who had previously done modelling work on vCJD. We worked on a collaborative project, funded by a National Health and Medical Research Council (NHMRC) partnership grant, to submit a case to the Therapeutics Goods Administration (TGA) to remove this deferral.

“The whole process was very involved, and it took five years to complete. Our modelling had a number of variables, including current pre-symptomatic vCJD cases in the UK, age at infection, genotype, and risk of exposure to cows with BSE between 1980 and 1996. We also used Australian Bureau of Statistics data to estimate the number of British people in Australia that may have been exposed. In addition, we used published date from a sheep model of this disease to see if it could be transmitted by transfusion and the effect of leucodepletion, which is done as part of modern transfusion practice.

“Using this model, we estimated that the risk of transmission of vCJD by blood from an Australian donor was one in 1.4 billion, and the event might happen every 65 years, as the worst-case scenario. To put that into context, the likelihood of being hit by an asteroid is probably in the same realm. As there has never been a reported case of vCJD in this country, the risk, in reality, is probably zero. We submitted our argument to the TGA, and they allowed us to remove this deferral on 25 July 2022.