Currently, the coronavirus disease 2019 (COVID-19) pandemic is still an ongoing and constant medical issue, and with upcoming new variants, vaccinations and boosters remain important. The safety of vaccines in patients after kidney transplantation is an essential problem, with thrombosis being one of the severe side effects and vaccine-induced immune thrombotic thrombocytopenia (VITT) revealed as the most commonly reported syndrome for thromboembolic events following COVID-19 vaccination. Here, we present two cases of kidney transplantation developing pulmonary embolism post-Moderna vaccination within 30 days without thrombocytopenia. The first case was a 52-year-old man with history of type II diabetes, hypertension and hyperlipidemia who had had cadaveric kidney transplantation in September 2008, where right leg swelling with claudication occurred 23 days after the second Moderna vaccination. The second case was a 57-year-old man with history of type II diabetes and glaucoma who had had living-related kidney transplantation in April 2013 and then complained of exertional dyspnea 26 days after administration of the third Moderna vaccine. The advantages of vaccination even in immunocompromised patients far outweigh the disadvantages, although clinicians must understand the risks of deep-vein thrombosis or even pulmonary embolism for such patients, which might not occur after just the first vaccination.
Keywords: COVID-19; Moderna vaccine; deep vein thrombosis; immunosuppressant; kidney transplantation; pulmonary embolism.