Abstract Background During the COVID-19 pandemic, there has been global administration of novel mRNA vaccines that are effective in reducing the burden of COVID-19. In tandem with this administration, mRNA vaccine-associated complications have been identified. One such complication is mRNA vaccine-associated pericarditis. Case summary This is a case of a 40-year old male who developed clinical pericarditis 3 days after his first dose of the Pfizer-BioNtech mRNA COVID-19 vaccination. The diagnosis of mRNA vaccine-induced pericarditis was confirmed on cardiac magnetic imaging and was resistant to numerous lines of medical therapy. These included substantial simple and opioid-based analgaesia, colchicine, prednisolone, interleukin-1 receptor antagonist therapy (anakinra), and a ketamine infusion that were all titrated over the course of eight hospital admissions. Ultimately, surgical pericardiectomy was performed that resulted in a favourable outcome. Discussion This case depicts an example of incessant mRNA vaccine-associated pericarditis, a known complication of the Pfizer-BioNtech mRNA COVID-19 vaccination. There is limited evidence guiding the therapy of mRNA-induced pericarditis especially when recurrent and resistant to simple analgaesia, colchicine, and steroids. Thus, this case represents a potential framework to help future cases of incessant mRNA vaccine-induced pericarditis.