Enoxaparin sodium/mRNA-1273

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An event is serious (based on the ICH definition) when the patient outcome is:

• * death

• * life-threatening

• * hospitalisation

• * disability

• * congenital anomaly

• * other medically important event

A 66-year-old man developed fever, chills, arthralgia and acute pulmonary emboli (PE) after receiving mRNA-1273 vaccine. In addition, he showed the presence of lupus anticoagulant (LA) signals during treatment with enoxaparin sodium for acute PE [not all dosages and routes stated].

The man presented to the emergency department with chief complaints of right flank pain and right pleuritic chest pain. Ten days prior to the presentation, he had received his second dose of the mRNA-1273 vaccine [Moderna SARS-CoV-2 vaccine]. After 24 hours of mRNA-1273 vaccine administration, he experienced fevers, chills and arthralgias that transitioned to progressive right-sided flank pain and pleuritic chest pain. He had also experienced fatigue. In the emergency department, his body temperature was 36.8°C, pulse rate was 65, BP was 138/84mm Hg, respiratory rate was 17 and oxygen saturation was 97% on room air. On physical examination, inspiratory crackles were heard at the right lung base. Moreover, laboratory studies showed elevated C-reactive protein and D-dimer levels. Subsequent PE-protocol CT angiogram of the chest revealed extensive multifocal pulmonary emboli involving both right and left lower lobe pulmonary arteries with evidence of right ventricular strain. Based on these examinations, a diagnosis of acute PE was made.

Therefore, the man was treated with SC enoxaparin sodium [enoxaparin] 1 mg/kg injection and labs were drawn approximately 3 hours later. A coagulation studies and thrombophilia workup were started. His prothrombin time (PT) and international normalised ratio (INR) were mildly prolonged and corrected when mixed 50:50 with normal pooled plasma. A dilute PT assay was positive, and the StaClot LA assay was borderline positive, suggestive of possible presence of LA signals. In addition, antiphospholipid IgM antibodies were weakly positive. SARS-CoV-2 spike antibodies were strongly positive, consistent with robust vaccine-induced immunity but no history of COVID-19. In view of results, it was concluded that he had developed acute PT secondary to mRNA-1273 vaccination and presence of LA signals was associated with enoxaparin sodium injection. Hence, his enoxaparin sodium treatment was changed to apixaban and he was discharged in stable condition with haematology follow-up [not all durations of treatments to reactions onsets stated].