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Wolfe C, Humar A. Buyer beware: The risks of donor-derived vaccine-induced thrombosis and thrombocytopenia [published online ahead of print, 2021 Aug 17]. Am J Transplant. 2021;10.1111/ajt.16802. doi:10.1111/ajt.16802
The emergence of the Sars‐CoV‐2 virus has posed unique challenges specific to transplantation and donation. For our transplant patients in our waiting lists, they have faced uncertainty, unsure if the pandemic will delay live‐saving transplants. In March 2021, vaccine‐induced thrombosis and thrombocytopenia (VITT) and central venous sinus thrombosis were recognized first in Europe with the Astra‐Zeneca ChAdOx01 nCoV‐19 vaccine and then in the United States with the Janssen Covid‐19 Ad.26.COV2.S vaccine. Not only did this represent a new risk to describe to our patients and colleagues, but because of the life‐threatening nature of this complication, we began receiving offers from donors who had died from VITT.1, 2
In this issue of the American Journal of Transplantation, we note reports from both Greenhall and Ushiro‐Lumb et al. and Loupy et al., contrasting recent European experience with vaccinated organ donors, who tragically died from VITT.3, 4 Mechanistically, our understanding of VITT is evolving with a recent Nature paper highlighting key features–it resembles heparin‐induced thrombocytopenia (HIT) in that it is associated with platelet‐activating antibodies against platelet factor 4 (PF4).5 In contrast to HIT, however, patients with VITT develop thrombosis and thrombocytopenia without heparin exposure. Antibodies formed after vaccination mimic heparin by tightly binding to a similar site on PF4, creating PF4 tetramers and inducing complexes to cascade and cluster, generating thrombosis via FcγRIIa‐dependent platelet activation.
Greenhall, Ushiro‐Lumb, and colleagues describe the early United Kingdom experience reviewing 13 consented organ donors, who suffered VITT following recent administration of the ChAdOx01 nCoV‐19 vaccine. Ten donors proceeded to donate 27 organs to 26 recipients. The donors were young, with a median age of just 34 years, and 85% were female. The average time from vaccination to hospital admission was just 10 days. Critically, 92% suffered from intracranial hemorrhage. Cerebral venous sinus thrombosis and extra‐cranial thrombosis occurred in 54% and 46% respectively.
Recipients fared worse than expected. Three recipients developed early allograft failure—in two livers and one kidney—requiring emergent explanation. Additionally, a further two kidneys had delayed graft function, and in total, six recipients suffered major thrombotic or hemorrhagic postoperative complications. Intriguingly, 3 out of 13 recipients tested had anti‐PF4 antibodies appear, suggesting a possible transmission of either passive antibodies or pathogenic donor lymphocytes, or at the very least, the de novo development of antibodies posttransplant. After median 19 days of follow‐up, only 78% of the allografts retained satisfactory function...
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There are no published case reports of transplant programs using organ donors with VITT secondary to the Janssen vaccine, which has been the adenovirus vector vaccine used in the United States. In general, however, the risks of VITT from the different adenovector vaccines appear similar.6, 7 On the surface, such a donor would be appealing: they are typically younger and with lower rates of chronic disease. Given the terminal event is usually a catastrophic central nervous system thrombosis or hemorrhage, potential donors with VITT generally have short hospital exposures and therefore less risk for active hospital‐acquired infection at the time of procurement....