fluid around heart; pericarditis; Blood pressure increased; Two leaky valves in Heart; fall; Concussion; feel woozy; nauseous; warm; dehydrated; This spontaneous case was reported by a consumer and describes the occurrence of PERICARDIAL EFFUSION (fluid around heart), PERICARDITIS (pericarditis) and BLOOD PRESSURE INCREASED (Blood pressure increased) in an 83-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product ADALIMUMAB (HUMIRA) solution for injection for Rheumatoid arthritis.    Concurrent medical conditions included Blood pressure high. Concomitant products included METHOTREXATE for an unknown indication.   On 10-Nov-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular use) 1 dosage form. On an unknown date, the patient started ADALIMUMAB (HUMIRA) (Subcutaneous use) 40 milligram. On 12-Nov-2021, the patient experienced FEELING HOT (warm) and DEHYDRATION (dehydrated). On an unknown date, the patient experienced PERICARDIAL EFFUSION (fluid around heart) (seriousness criterion medically significant), PERICARDITIS (pericarditis) (seriousness criterion medically significant), BLOOD PRESSURE INCREASED (Blood pressure increased) (seriousness criterion medically significant), HEART VALVE INCOMPETENCE (Two leaky valves in Heart), FALL (fall), CONCUSSION (Concussion), DIZZINESS (feel woozy) and NAUSEA (nauseous). At the time of the report, PERICARDIAL EFFUSION (fluid around heart), PERICARDITIS (pericarditis), BLOOD PRESSURE INCREASED (Blood pressure increased), HEART VALVE INCOMPETENCE (Two leaky valves in Heart), FEELING HOT (warm), DEHYDRATION (dehydrated), FALL (fall), CONCUSSION (Concussion), DIZZINESS (feel woozy) and NAUSEA (nauseous) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood pressure measurement: 250/112, high. On an unknown date, Cardiac function test: for patient's age, it was working properly, two leaky valves.. On an unknown date, Chest X-ray: Possible heart problems/ fluid around my heart or pericarditis.. On an unknown date, Computerised tomogram: no bleeding was noted..         The patient had other concomitant therapy of different combinations of blood pressure drugs. The reporter's causality for the event(s) of fluid around heart and pericarditis with Moderna COVID-19 vaccine (Elasomeran) was Reasonable Possibility.  No treatment medications were reported. Company comment This spontaneous case concerns an 83-year-old female patient with medical history of Rheumatoid arthritis in treatment with Methotrexate and Adalimumab, received the third dose of mRNA-1273 and experienced the expected, serious (medically significant), event of pericarditis and unexpected, serious (medically significant), events of pericardial effusion and blood pressure increased. The events onset dates were not provided, thus, exact latency between vaccination and onset of the events could not be assessed. The non-serious events of hot and dehydration occurred 2 days after the third dose. On an unknown date, blood pressure measurement was reported as high: 250/112.  It was reported that a cardiac function test was performed and for the patient's age, it was working properly with two leaky valves. No further clinical information was provided for review. The medical history of Rheumatoid arthritis could be associated with pericarditis, pericardial effusion, and heart valve incompetence, so, could be a confounder. Heart valve incompetence was assessed as not related because of the nature of the event, lack of biological plausibility and the patient's age could be a risk factor for heart valve incompetence. The non-serious events of nausea, dizziness, hot, dehydration, fall and concussion could be associated with each other. Fall was assessed as not related due to lack of biological plausibility. Concussion is a type of traumatic brain injury, so, assessed as not related because of the lack of biological plausibility. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.