Abstract
mRNA vaccines against the novel coronavirus infection (coronavirus disease 2019 [COVID-19) are effective in preventing severe disease. However, side effects, such as injection site pain, fatigue, and headache, are frequent, and although rare, cases of suspected myocarditis and endocarditis have also been reported. In the present study, we report on a case of suspected rhabdomyolysis following vaccination with an omicron-compatible bivalent coronavirus-modified uridine RNA vaccine (SARS-CoV-2) (Comirnaty®, active ingredients: tozinameran and famtozinameran), although no adverse reactions were observed after four doses of mRNA vaccine against the monovalent origin strain of the new coronavirus. The patient was a man in his 70s. Two days after vaccination, a visiting helper found him crawling on the floor and unable to stand because he felt sluggish upon waking up. He was transported to our hospital by ambulance and underwent a clinical examination, which revealed a serum creatine kinase (CK) level of 7,455 U/L and urinary myoglobin level of 28,400 ng/mL, both of which were high; he was admitted with a diagnosis of rhabdomyolysis. The patient was taking rabeprazole, which has been reported to cause rhabdomyolysis, and a causal relationship with the vaccine was suspected, as the patient had been taking the drug for a long time and had been vaccinated with the omicron-responsive bivalent vaccine two days earlier. Thereafter, saline was administered daily. The patient was followed up, and the CK level decreased over time, with no onset of acute renal dysfunction, and the dysmobility disappeared. In the present case, the pharmacist investigated the patient’s medication history and identified the suspected medication, which may have led to the early diagnosis of rhabdomyolysis and subsequent treatment.
