PERICARDITIS; This 69-year-old, male subject was participating in a study and experienced the non-serious adverse event of special interest (AESI) of pericarditis.  The subject's medical history, as provided by the investigator, included glaucoma and benign prostatic hyperplasia (BPH). Medical history from medical records included mitral valve prolapse, glaucoma, uncoded history of ophthalmic migraine migraines, status post transurethral resection of the prostate (TURP), hematuria and urinary catheter dysfunction, skin lesion excision and vasectomy. Concomitant medications included bimatoprost, dorzolamide hydrochloride/ timolol maleate, finasteride, and doxycycline.  Prior to event onset, the subject received intramuscular mRNA-1273 (Dose 3, booster) for SARS-CoV-2 vaccination on 12 Oct 2021, approximately 2 months and 3 days before onset of the event.  On 14 Dec 2021, the subject experienced pericarditis. The subject had an onset of upper respiratory infection (URI) 10 days prior to admission with sinus congestion, rhinorrhea, cough, postnasal drip, low grade fevers, headaches, and sinus pressure. Two days  prior to admission, the subject developed left anterior chest pain, which was treated with ibuprofen. Symptoms of cough and Valsalva were progressed and were better with leaning forward. The subject had received doxicillin from 12-16 Dec-2021 for bacterial sinusitis. There was no dyspnea, wheezing, orthopnea, tachycardia and palpitations, paroxysmal nocturnal dyspnea (PND), lightheadedness or dizziness. He was an avid runner. His activity had been low since onset of symptoms. Several family members also had similar symptoms, had negative COVID-19 tests and were fully vaccinated.  Vital signs were blood pressure 140/80, pulse 56, body temperature 36.2 degrees Celsius (temporal), and oxygen saturation 100 percent (%). Laboratory results included elevated inflammatory markers C-reactive protein (CRP) high sensitivity 26.5 mg/dl (normal 0.0-3.0) and erythrocyte sedimentation rate (ESR) 21 mm/h (normal 0-20). A chest x-ray was normal. An electrocardiogram (ECG) showed an abnormal ECG (unspecified) but was noted as unchanged from previous. The subject had new lower left sternal border (LLSB) along with recent URI which concerned for pericarditis. Treatment for the event included oral ibuprofen and oral colchicine. URI symptoms were resolved since initiation of pericarditis. Visit diagnosis included precordial pain.  The subject received all scheduled doses of study drug prior to the event; therefore, action taken with study drug in response to the event was not applicable.  The event, pericarditis, was reported as resolved on 21 Dec 2021.   The investigator assessed the event, pericarditis, as not related to study drug and not related to study procedure.  Follow up received on 26 Jan 2022 and 27 Jan 2022, included updated event outcome, history of presenting illness, medical history, laboratory results, diagnostic results, and treatment medications from medical records.  Follow-up received on 14 Feb 2022 included the results of diagnostic testing.   Follow-up received on 24 Feb 2022 included no new information.  Follow-up received on 23 Mar 2022 included updated concomitant medications, event outcome, and event end date.  Company Comment: This case concerns a 69-year-old, male subject, with medical history of mitral valve prolapse, glaucoma, ophthalmic migraine migraines and status post transurethral resection of the prostate among others, who experienced the non-serious adverse event of special interest (AESI) of pericarditis. The event occurred approximately 15 months 12 days after the first dose of mRNA-1273 and 2 months and 3 days after the third (booster) dose of mRNA-1273. The event was reported as resolved. The event was considered unrelated to the study drug per the sponsor and reporter's assessment. The event might be explained by recent upper respiratory infection.; Reporter's Comments: Company Comment: This case concerns a 69-year-old, male subject, with medical history of mitral valve prolapse, glaucoma, ophthalmic migraine migraines and status post transurethral resection of the prostate among others, who experienced the non-serious adverse event of special interest (AESI) of pericarditis. The event occurred approximately 15 months 12 days after the first dose of mRNA-1273 and 2 months and 3 days after the third (booster) dose of mRNA-1273. The event was reported as resolved. The event was considered unrelated to the study drug per the sponsor and reporter's assessment. The event might be explained by recent upper respiratory infection.