Appendicitis; Had pulmonary Embolism; It felt like he was having a heart attack, My heart was pounding; Woke up with the worse stomach pain; It felt like he was having a heart attack; Calf pain; Missed 2nd dose; This spontaneous case was reported by a consumer and describes the occurrence of APPENDICITIS (Appendicitis), PULMONARY EMBOLISM (Had pulmonary Embolism), PALPITATIONS (It felt like he was having a heart attack, My heart was pounding), ABDOMINAL PAIN UPPER (Woke up with the worse stomach pain) and CARDIAC DISCOMFORT (It felt like he was having a heart attack) in a 37-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 026B21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.    On 06-Apr-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 06-Apr-2021, the patient experienced CARDIAC DISCOMFORT (It felt like he was having a heart attack) (seriousness criteria hospitalization, medically significant and life threatening). On 07-Apr-2021, the patient experienced PALPITATIONS (It felt like he was having a heart attack, My heart was pounding) (seriousness criteria hospitalization, medically significant and life threatening) and ABDOMINAL PAIN UPPER (Woke up with the worse stomach pain) (seriousness criteria hospitalization, medically significant and life threatening). On an unknown date, the patient experienced APPENDICITIS (Appendicitis) (seriousness criteria hospitalization, medically significant and life threatening), PULMONARY EMBOLISM (Had pulmonary Embolism) (seriousness criteria hospitalization, medically significant and life threatening), PAIN IN EXTREMITY (Calf pain) and PRODUCT DOSE OMISSION ISSUE (Missed 2nd dose). The patient was treated with Surgery for Appendicitis. At the time of the report, APPENDICITIS (Appendicitis), PULMONARY EMBOLISM (Had pulmonary Embolism), PALPITATIONS (It felt like he was having a heart attack, My heart was pounding), ABDOMINAL PAIN UPPER (Woke up with the worse stomach pain), CARDIAC DISCOMFORT (It felt like he was having a heart attack) and PAIN IN EXTREMITY (Calf pain) outcome was unknown and PRODUCT DOSE OMISSION ISSUE (Missed 2nd dose) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Ultrasound scan: pulmonary embolism (abnormal) pulmonary embolism.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.       No concomitant product information was provided by the reporter.  Patient reportedly took blood thinners as a treatment medication.  This is a case of dose omission for this 33-year-old male. Regarding the other adverse events, based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded.  Company Comment: This is a case of dose omission for this 33-year-old male. Regarding the other adverse events, based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded.; Sender's Comments: This is a case of dose omission for this 33-year-old male. Regarding the other adverse events, based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded.