Couldn't breathe; My chest was killing me; Ended up with a blood clot in my lungs; Had a bad reaction; Has felt terrible/ Never felt anything like this in my life; Felt pain in the bend of her left arm/ The inside of the bend of her arm was real sore; This spontaneous case was reported by a consumer and describes the occurrence of DYSPNOEA (Couldn't breathe), CHEST DISCOMFORT (My chest was killing me) and PULMONARY THROMBOSIS (Ended up with a blood clot in my lungs) in a 66-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 048F21A and 939901) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 21-Aug-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 19-Sep-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 04-Oct-2021, the patient experienced DYSPNOEA (Couldn't breathe) (seriousness criterion hospitalization) and CHEST DISCOMFORT (My chest was killing me) (seriousness criterion hospitalization). In October 2021, the patient experienced PULMONARY THROMBOSIS (Ended up with a blood clot in my lungs) (seriousness criterion medically significant), VACCINATION COMPLICATION (Had a bad reaction), FEELING ABNORMAL (Has felt terrible/ Never felt anything like this in my life) and VACCINATION SITE PAIN (Felt pain in the bend of her left arm/ The inside of the bend of her arm was real sore). The patient was hospitalized on 04-Oct-2021 due to CHEST DISCOMFORT and DYSPNOEA. At the time of the report, DYSPNOEA (Couldn't breathe), CHEST DISCOMFORT (My chest was killing me), PULMONARY THROMBOSIS (Ended up with a blood clot in my lungs), VACCINATION COMPLICATION (Had a bad reaction), FEELING ABNORMAL (Has felt terrible/ Never felt anything like this in my life) and VACCINATION SITE PAIN (Felt pain in the bend of her left arm/ The inside of the bend of her arm was real sore) outcome was unknown.            No concomitant medications were provided. Treatment medications included blood thinners for 6 months.  The patient stated that was still under care and would be for 6 months. The patient also stated that the hematologist believed the blood clot was related to the vaccine as it occurred in the same arm and it was two weeks after the second vaccine.  Company comment: This case concerns a  66-year-old, female patient with no relevant medical history, who experienced the unexpected events of Dyspnea, Chest Discomfort, and Pulmonary Thrombosis. The events occurred approximately 16 days after the second dose of mRNA-1273 (Moderna Covid-19 Vaccine). The rechallenge was not applicable as events occurred after second dose. The benefit-risk relationship of mRNA-1273 (Moderna Covid-19 vaccine) is not affected by this report.; Sender's Comments: This case concerns a  66-year-old, female patient with no relevant medical history, who experienced the unexpected events of Dyspnea, Chest Discomfort, and Pulmonary Thrombosis. The events occurred approximately 16 days after the second dose of mRNA-1273 (Moderna Covid-19 Vaccine). The rechallenge was not applicable as events occurred after second dose. The benefit-risk relationship of mRNA-1273 (Moderna Covid-19 vaccine) is not affected by this report.