This spontaneous case was reported by a consumer and describes the occurrence of DYSPNOEA (breathing problem, have been in and out of the hospital due to breathing problem), CHEST PAIN (not serious chest pain but mild), MUSCLE DISCOMFORT (muscle issues in their leg), THROMBOCYTOPENIA (platelets count were low, Platelet levels decreased after booster) and CHEST DISCOMFORT (Feeling weak on left side of chest when laying down after booster) in a 70-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 048C21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below. Previously administered products included for COVID-19 vaccination: Pfizer COVID-19 vaccine (First shot) on 12-Mar-2021 and Pfizer COVID-19 vaccine (2nd shot) on 12-Apr-2021. Past adverse reactions to the above products included No adverse event with Pfizer COVID-19 vaccine and Pfizer COVID-19 vaccine. Concurrent medical conditions included Lupus syndrome (Patient have seen Rheumatologist for their Lupus), Hypertension and Cholesterol. Concomitant products included SIMVASTATIN for Cholesterol, AMLODIPINE for Hypertension. On 02-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 02-Dec-2021, the patient experienced BACK PAIN (Back pain after booster), CHILLS (serious chills in the winter, Severe chills after booster), FATIGUE (Fatigue after booster) and INTERCHANGE OF VACCINE PRODUCTS (INTERCHANGE OF VACCINE PRODUCT). In January 2022, the patient experienced DYSPNOEA (breathing problem, have been in and out of the hospital due to breathing problem), CHEST PAIN (not serious chest pain but mild), MUSCLE DISCOMFORT (muscle issues in their leg), THROMBOCYTOPENIA (platelets count were low, Platelet levels decreased after booster), CHEST DISCOMFORT (Feeling weak on left side of chest when laying down after booster), MENTAL DISORDER (Psychological problems per MD after booster) and MYALGIA (Aching all over the body after booster). In January 2022, CHILLS (serious chills in the winter, Severe chills after booster) outcome was unknown. At the time of the report, DYSPNOEA (breathing problem, have been in and out of the hospital due to breathing problem) had not resolved, CHEST PAIN (not serious chest pain but mild), MUSCLE DISCOMFORT (muscle issues in their leg), THROMBOCYTOPENIA (platelets count were low, Platelet levels decreased after booster), CHEST DISCOMFORT (Feeling weak on left side of chest when laying down after booster), MENTAL DISORDER (Psychological problems per MD after booster) and FATIGUE (Fatigue after booster) outcome was unknown, BACK PAIN (Back pain after booster) and MYALGIA (Aching all over the body after booster) was resolving and INTERCHANGE OF VACCINE PRODUCTS (INTERCHANGE OF VACCINE PRODUCT) had resolved. DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 21-Dec-2021, SARS-CoV-2 antibody test: positive (Positive) Positive. On an unknown date, Cardiac stress test: normal (normal) Normal. On an unknown date, Computerised tomogram: normal (normal) Normal. On an unknown date, Echocardiogram: normal (normal) Normal. On an unknown date, Electrocardiogram: normal (normal) Normal. On an unknown date, Magnetic resonance imaging: normal (normal) Normal. On an unknown date, Platelet count: low (Low) Low. For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments. Patient states that they had serious chills in the winter when they were walking in the street couple month ago and took them about 20 minutes for their body to warm when went to warm place. It was reported that Myocarditis was ruled out. Patient had Physical therapy of knee prior to vaccination which continued after vaccination, the vaccine did not affect the knee. Patient stated that overall his pain level has decreased. Patient had undergone Colonoscopy. No treatment medications were reported. Company comment: This is a spontaneous case of interchange of vaccine product (received as first and second dose TOZINAMERAN vaccine) concerning a 70-year-old male patient with medical condition of lupus who experienced the unexpected AESI thrombocytopenia along with several non- serious events such as dyspnoea, chest pain and back pain among others after a booster dose of mRNA-1273 vaccine was administered. Medical condition of lupus and vaccination with TOZINAMERAN remain as confounders. After booster was given patient experienced aching all over the body, weakness on left side of chest when laying down, platelet levels decreased, fatigue, back pain and some episodes of severe chills. He visited the hospital emergency room several times; echo, CT, EKG, stress test, and MRI with contrast were done, all showed normal. Myocarditis was ruled out. The doctor told him that he was having psychological problems. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report. Most recent FOLLOW-UP information incorporated above includes: On 28-Mar-2022: Live Follow up received contains Significant information, includes Patient, reporter information, New events, Medical history, Drugs start date, batch lot number and lab data were added. Sender's Comments: This is a spontaneous case of interchange of vaccine product (received as first and second dose TOZINAMERAN vaccine) concerning a 70-year-old male patient with medical condition of lupus who experienced the unexpected AESI thrombocytopenia along with several non- serious events such as dyspnoea, chest pain and back pain among others after a booster dose of mRNA-1273 vaccine was administered. Medical condition of lupus and vaccination with TOZINAMERAN remain as confounders. After booster was given patient experienced aching all over the body, weakness on left side of chest when laying down, platelet levels decreased, fatigue, back pain and some episodes of severe chills. He visited the hospital emergency room several times; echo, CT, EKG, stress test, and MRI with contrast were done, all showed normal. Myocarditis was ruled out. The doctor told him that he was having psychological problems.  The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.