This spontaneous case was reported by a consumer and describes the occurrence of RIGHT VENTRICULAR FAILURE (was diagnosed with Right-Sided Heart Failure), PULMONARY EMBOLISM (was diagnosed with Saddle pulmonary embolism (SPE)), PAIN IN EXTREMITY (My leg hurts), BACK PAIN (my back hurts), ABDOMINAL PAIN UPPER (my stomach hurts), BLOOD PRESSURE FLUCTUATION (My blood pressure goes up and down), FATIGUE (I'm getting really tired) and DYSPNOEA (shortness of breath) in a 58-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 003B21A) for COVID-19 vaccination. Concurrent medical conditions included Hypertension (High blood pressure that controlled with her medication) since 2019, COPD (patient is now stable and is taking two inhalers) since 2015 and Drug allergy (Flagyl, Keflex, Reglan). Concomitant products included LISINOPRIL for Hypertension, FLUTICASONE FUROATE, UMECLIDINIUM BROMIDE, VILANTEROL TRIFENATATE (TRELEGY ELLIPTA), SALBUTAMOL SULFATE (ALBUTEROL SULFATE), APIXABAN (ELIQUIS), FLUOXETINE, ALPRAZOLAM and HYDROCHLOROTHIAZIDE for an unknown indication. On 03-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 04-Mar-2021, the patient experienced PAIN IN EXTREMITY (My leg hurts) (seriousness criterion hospitalization), BACK PAIN (my back hurts) (seriousness criterion hospitalization), ABDOMINAL PAIN UPPER (my stomach hurts) (seriousness criterion hospitalization), BLOOD PRESSURE FLUCTUATION (My blood pressure goes up and down) (seriousness criterion hospitalization), FATIGUE (I'm getting really tired) (seriousness criterion hospitalization) and DYSPNOEA (shortness of breath) (seriousness criterion hospitalization). On an unknown date, the patient experienced RIGHT VENTRICULAR FAILURE (was diagnosed with Right-Sided Heart Failure) (seriousness criteria hospitalization, medically significant and life threatening) and PULMONARY EMBOLISM (was diagnosed with Saddle pulmonary embolism (SPE)) (seriousness criteria hospitalization, medically significant and life threatening). At the time of the report, RIGHT VENTRICULAR FAILURE (was diagnosed with Right-Sided Heart Failure), PULMONARY EMBOLISM (was diagnosed with Saddle pulmonary embolism (SPE)), PAIN IN EXTREMITY (My leg hurts), BACK PAIN (my back hurts), ABDOMINAL PAIN UPPER (my stomach hurts), BLOOD PRESSURE FLUCTUATION (My blood pressure goes up and down), FATIGUE (I'm getting really tired) and DYSPNOEA (shortness of breath) outcome was unknown. DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Blood pressure measurement: 77/59mmhg on her right and 84/52mmhg on her left a (Low) 77/59mmHg on her right and 84/52mmHg on her left arm. The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown. For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments. Treatment information was not provided. Patient reported that she was ok but sometimes felt very short of breath. Patient Blood pressure reading was always high but not now it goes up and down, patient was advised by cardiologist to take Lisinopril 20mg when her blood pressure reading gets high. She has not taken medication for over a week. Company comment: This spontaneous case concerns a 58-year-old female patient, with medical history of hypertension and COPD, who experienced the serious (Life threatening, hospitalization, medically significant) unexpected AESI of right sided heart failure and saddle pulmonary embolism. Patient had leg pain, back pain and stomach pain 1 day after receiving the first dose of mRNA 1273 COVID-19 vaccine. Patient was hospitalized and diagnosed with right sided heart failure and saddle pulmonary embolism. Patient also had unstable blood pressure (goes up and down), fatigue and dyspnea. No information was provided regarding diagnostic investigations and treatment. The patient's history of hypertension and COPD remain as confounders to the events. The benefit-risk relationship of mRNA 1273 vaccine is not affected by this report. Sender's Comments: This spontaneous case concerns a 58-year-old female patient, with medical history of hypertension and COPD, who experienced the serious (Life threatening, hospitalization, medically significant) unexpected AESI of right sided heart failure and saddle pulmonary embolism. Patient had leg pain, back pain and stomach pain 1 day after receiving the first dose of mRNA 1273 COVID-19 vaccine. Patient was hospitalized and diagnosed with right sided heart failure and saddle pulmonary embolism. Patient also had unstable blood pressure (goes up and down), fatigue and dyspnea. No information was provided regarding diagnostic investigations and treatment. The patient's history of hypertension and COPD remain as confounders to the events. The benefit-risk relationship of mRNA 1273 vaccine is not affected by this report.