ABSTRACT
Introduction: The systemic side-effects of anti-SARS CoV-2 vaccination are described for all types of vaccines. We describe a case of a likely adverse reaction to the Spikevax Moderna vaccine, manifested by septic arthritis of the left sternoclavicular joint, mediastinitis and pulmonary embolism. Case Report: 22-year- old female soldier developed symptoms of fever, chest and limb discomfort in her left upper arm around 10 days after receiving her first dose of Spikevax Moderna vaccine, necessitating hospitalization 14 days after. Septic arthritis of the left sternoclavicular joint, mediastinitis, deep vein thrombosis of the left upper limb, and pulmonary embolism were diagnosed. The blood culture result showed the development of Staphylococcus aureus. The patient was treated with antibiotic therapy and with anticoagulant therapy. There was a rapid improvement in clinical conditions, allowing the patient to be discharged 10 days after admission. Conclusions: The vaccination's causative role in the formation of the clinical picture is extremely likely in this case, but with a plausible not-specific pathogenetic mechanisms. There have been reports of septic arthritis following SARS CoV2 vaccination, especially of the shoulder joint, but the novelty of our finding stems from the fact that it would be the first case of septic arthritis after vaccination involving a sternoclavicular localization. This case emphasizes the importance of maintaining a high degree of attention when administering vaccines and keeping a close eye on the patient in the days after the vaccine.