PULMONARY EMBOLUS; This report was received from business partner GlaxoSmithKline, with assigned Manufacturer Control Number of US2021GSK252161.  Case Description: This 53-year-old male subject was enrolled in a study.  The subject received COVID-19 Vaccine Moderna (intramuscular) .5 ml on 29th November 2021 12:06, for prophylaxis.  The subject's past medical history included rectal prolapse, abdominal hernia, cataract (Right eye), cataract (Left eye), cataract extraction (removal right eye), nephrolithiasis, ex-smoker (Cigars) and cataract extraction (Removal left eye). Concurrent medical conditions included erectile dysfunction, hyperlipidemia, nausea (Azithromycin drug allergy), alcohol use (Subject reported two units (wine/beer) per month at screening visit.) and seasonal allergy. Concomitant products included INFLUENZA VACCINE, COVID-19 VACCINE (COVID 19 VACCINE), tadalafil (Cialis), atorvastatin calcium (Lipitor), paracetamol (Acetaminophen), enoxaparin, iohexol, rivaroxaban (Xarelto), ketorolac, ondansetron (Ondansetron Odt) and oxycodone hydrochloride + paracetamol (Percocet).  On 1st December 2021, 2 days after receiving COVID-19 Vaccine Moderna, the subject developed severe - grade 3 pulmonary embolism. Serious criteria included life threatening and other:medically important event. COVID-19 Vaccine Moderna was interrupted. The outcome of pulmonary embolism was not recovered/not resolved.  The investigator considered that there was a reasonable possibility that the pulmonary embolism may have been caused by COVID-19 Vaccine Moderna.  Diagnostic results (unless otherwise stated, normal values were not provided): On 3rd December 2021, Angiogram result was right lower Lobe subsegmental pulmonary embolus, Chest X-ray result was small right pleural effusion, Echocardiogram result was normal, Electrocardiogram result was Normal, Fibrin D dimer increased result was 1.20 and Oxygen saturation result was 97 percent.  Investigator Comment: Subject received Moderna booster vaccination per protocol 29 Nov 2021. Subject developed right flank pain 01 Dec 2021 which progressed over following two days. Subject presented to local emergency department (ED) 03 Dec 2021 for evaluation. Pain described as sharp and severe. Subject's oxygen saturation 97% on admission.Relevant studies performed in the ed included an elevated d dimer (1.20), Chest Radiograph with small right pleural effusion, CT angiography with right lower Lobe subsegmental pulmonary embolus. ECG and echocardiogram normal. Subject observed in ed for approximately 13 hours and discharged to home on xarelto 15 Mg twice daily. Subject had long car ride in October 2021. No prior history of DVT or PE.  Additional details: This case contains an event assessed by the investigator as a serious adverse event of special interest (AESI). Rational for related assessment: The absence of other known risk factors for pulmonary embolus 2. The time frame of the PE as it relates to vaccination. Rational for seriousness criteria used: seriousness criteria this is hypothetical as a pulmonary embolus is potentially life threatening event.  Analysis of Similar Events:  On 18 Jan 2022, the safety database was searched for events similar to Pulmonary embolism using the following search criteria: PT: Pulmonary embolism. As of 18 Jan 2022, under IND 019745 for mRNA-1273, 40 similar events were retrieved, including the current index case. None of these cases were previously submitted as IND Safety Reports.  The index case concerns a 53-year-old male subject who experienced pulmonary embolism 2 days after receiving booster dose of mRNA-1273. The subject had no apparent immediate risks factors. It was reported that the subject had had a long car ride on the month prior to the event and also that the subject was an ex-smoker, however dates for smoking cessation were not provided. The Investigator considered the event possibly related to mRNA-1273 based on temporal association and lack of known risk factors.   The other 39 cases of pulmonary embolism  retrieved were assessed as not related to m-RNA-1273.  Based on review of available data, the Sponsor cannot rule out a possible cause and effect relationship between administration of mRNA-1273 and the occurrence of pulmonary embolism  After review of the clinical details and investigator comments pertaining to this adverse event, and based upon experience to date, the Sponsor does not believe that changes to the conduct of this clinical trial are warranted. The Company will continue to monitor these and other serious adverse events reported in association with the RA and will communicate any relevant changes to the protocol, Informed Consent  Form, Investigator's Brochure, and/or Core Safety Information.  Company comment: This case concerns a 53-year-old male subject with a history of rectal prolapse, abdominal hernia, cataract (Right eye), cataract (Left eye), cataract extraction (removal right eye), nephrolithiasis, ex-smoker (Cigars) and cataract extraction (Removal left eye), who experienced the unexpected adverse event of special interest of pulmonary embolus. The event occurred 3 days after receiving mRNA-1273. Action taken was reported as dose interrupted.  The event was reported as not resolved. The event was assessed as related to mRNA-1273 in agreement with the Investigator based on temporal association and absence of other immediate risk factors. It was reported that the subject had a long car ride in October 2021 the month prior to the event and it was also mentioned that the subject is an ex-smoker although dates for smoking cessation were not provided.; Reporter's Comments: Company comment: This case concerns a 53-year-old male subject with a history of rectal prolapse, abdominal hernia, cataract (Right eye), cataract (Left eye), cataract extraction (removal right eye), nephrolithiasis, ex-smoker (Cigars) and cataract extraction (Removal left eye), who experienced the unexpected adverse event of special interest of pulmonary embolus. The event occurred 3 days after receiving mRNA-1273. Action taken with IP was reported as dose interrupted.  The event was reported as not resolved. The event was assessed as related to mRNA-1273 in agreement with the Investigator based on temporal association and absence of other immediate risk factors. It was reported that the subject had a long car ride in October 2021 the month prior to the event and it was also mentioned that the subject is an ex-smoker although dates for smoking cessation were not provided.