COVID-19; This literature-study case was reported in a literature article and describes the occurrence of COVID-19 PNEUMONIA (COVID-19) in a 69-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     The patient's past medical history included Liver cirrhosis since an unknown date and Cessation of smoking (He had a history of 10-year pack per day (PPD), quit smoking over 30 years ago). Concurrent medical conditions included Essential hypertension, Type 2 diabetes mellitus, Obstructive sleep apnea hypopnea syndrome and Hypothyroidism.    On 09-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 10-Jan-2021, the patient experienced COVID-19 PNEUMONIA (COVID-19) (seriousness criterion hospitalization prolonged). The patient was treated with REMDESIVIR (intravenous) for COVID-19, at an unspecified dose and frequency; REMDESIVIR (oral) for COVID-19, at an unspecified dose and frequency; BARICITINIB (oral) for COVID-19, at an unspecified dose and frequency; TOCILIZUMAB for COVID-19, at a dose of 3 dosage form; PREDNISONE (oral) for COVID-19, at a dose of 20 milligram and CONVALESCENT PLASMA COVID-19 for COVID-19, at an unspecified dose and frequency. At the time of the report, COVID-19 PNEUMONIA (COVID-19) was resolving. Possible    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Angiogram: negative (Negative) The CT angiogram of the chest was negative for pulmonary embolism.. On an unknown date, Aspartate aminotransferase (6-29  u/l): 44 u/l (High) 44 U/L. On an unknown date, Blood alkaline phosphatase (37 u/l-153 u/l): 272 u/l (High) 272 U/L. On an unknown date, Blood bilirubin (0.2 mg/dl-1.2 mg/dl): 1.8  mg/dl (High) 1.8  mg/dL. On an unknown date, Blood fibrinogen (190  mg/dl-480  mg/dl): 730 mg/dl (High) 730 mg/dL. On an unknown date, Blood lactate dehydrogenase (98 u/l-192 u/l): 220 u/l (High) 220 U/L. On an unknown date, Computerised tomogram: pneumonia The CT scan of the chest in the emergency room showed ground-glass infiltrates in both lungs and associated interstitial infiltrates, consistent with COVID-19 multifocal pneumonia. On an unknown date, Fibrin D dimer: 2.45 ug/ml 2.45 ug/mL.Rreference range  lesser than0.44 ug/mL. On an unknown date, Imaging procedure: the imaging showed a new pneumo- mediastinum The imaging showed a new pneumo- mediastinum and repeated imaging confirmed a pneumo-mediastinum wi Repeated imaging confirmed a pneumo-mediastinum with no pneumothorax. On an unknown date, Oxygen saturation: decreased His oxygen saturation on the pulse oximetry at home was 90% initially but later dropped to 85% over the next three days.. On an unknown date, Polymerase chain reaction: positive tested positive for COVID-19 by PCR and positive In the emergency room, he was hypoxic, re-tested for COVID-19 infection, which was positive.. On an unknown date, SARS-CoV-2 antibody test: positive (Positive) Positive. On an unknown date, Ultrasound Doppler: negative The lower extremity doppler study was negative for DVT;.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered COVID-19 PNEUMONIA (COVID-19) to be possibly related.    He regularly uses continuous positive airway pressure. A day after receiving the vaccine, he started having body aches and headaches. Later, his headache improved, but he progressively developed shortness of breath. He presented to the emergency room with worsening shortness of breath and denied cough, fever, chest pain or palpitations, trouble with urination, and bowel movements. His hepatic function panel and renal function panel were within normal limits. At the time of admission, laboratory parameters were normal for the most part. He was initially treated with intravenous steroids, oxygen supplements, and intravenous remdesivir. When there was no clinical improvement over the next 48 hours, he was started on combination of oral baricitinib and remdesivir as this combination was proven superior to remdesivir alone in the length of stay of hospitalized patients from COVID-19. There was still no improvement after 72 hours, and two doses of tocilizumab were administered. However, he continued to deteriorate with progressive hypoxia, requiring up to 15 L oxygen through a high-flow nasal cannula. Convalescent plasma was routinely administered to COVID-19 patients during that period. After much debate, it was decided not to administer convalescent plasma. Over the next 2 days, his hypoxia worsened, and the imaging showed a new pneumo- mediastinum. He was then transferred to the intensive care unit for further management and completed the ten-day course of IV remdesivir therapy. He was also given intermittent diuretics, high-dose IV steroids. His liver enzymes, renal function panel, and inflammatory markers were within normal limits. He was eventually transferred back to the medical floor and discharged home with one-liter supplemental oxygen. He was advised to wait for three months before receiving the second dose of the vaccine.   Most recent FOLLOW-UP information incorporated above includes: On 21-Oct-2021: Followup received by safety on 21-Oct-2021 doesnot contain any new information.; Sender's Comments: This literature review case concerns a 69 year old male with a history of obstructive sleep apnea and a 10 pack year history of smoking who experienced the serious, unlisted medical event of COVID-19 pneumonia the day after the first dose of mRNA-1273. Re-challenge is unknown as no information about further dosing is reported. The history of obstructive sleep apnea and 10 pack years of smoking remains a confounder as these can exacerbate the symptoms. Benefit-risk relationship of mRNA-1273 is not affected by this report.