Organizing pneumonia; This literature-non-study case was reported in a literature article and describes the occurrence of ORGANISING PNEUMONIA (Organizing pneumonia) in a 47-year-old male patient who received mRNA-1273.815 (SPIKEVAX 2023-2024) for COVID-19 prophylaxis.   LITERATURE REFERENCE:    The patient's past medical history included Ex-smoker. Family history included Pulmonary fibrosis since an unknown date.    On an unknown date, the patient received first dose of mRNA-1273.815 (SPIKEVAX 2023-2024) (unknown route) 1 dosage form. On an unknown date, the patient experienced ORGANISING PNEUMONIA (Organizing pneumonia) (seriousness criterion medically significant). At the time of the report, ORGANISING PNEUMONIA (Organizing pneumonia) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Biopsy lung: Confirmed organizing pneumonia (OP). On an unknown date, Bronchoalveolar lavage: showed no diffuse alveolar hemorrhage or eosinophilia. On an unknown date, Computerised tomogram thorax: revealed extensive bilateral consolidation along with subpleural foci of ground-glass opacities (GGOs). On an unknown date, Mycoplasma test: infectious workup was notable only for positive Mycoplasma pneumoniae IgG, but negative IgM. On an unknown date, Rheumatological examination: Negative.     The action taken with mRNA-1273.815 (SPIKEVAX 2023-2024) (Unknown) was unknown.   For mRNA-1273.815 (SPIKEVAX 2023-2024) (Unknown), the reporter considered ORGANISING PNEUMONIA (Organizing pneumonia) to be related.    Concomitant medication was not reported.  Patient developed low-grade fevers, dry cough, and dyspnea, one week after his first mRNA vaccine (Moderna). Patient symptoms initially improved with corticosteroids, and patient received 1 additional mRNA vaccine dose that correlated to worsening of disease. Patient symptoms and radiographic abnormalities returned when corticosteroids were tapered and patient remains corticosteroid dependent today.  Author concluded that although a definitive causal relationship cannot be established, SARS-CoV-2 mRNA vaccination was temporally associated with the development of severe organizing pneumonia (OP).  Company Comment: This is a literature non-study case concerning a 47-year-old, male patient with a history of smoking (not current) and family history of pulmonary fibrosis since an unknown date, who experienced the serious (due to medically significant) unexpected event of Organizing pneumonia (OP). The event occurred approximately one week after the first dose of mRNA-1273.815 (SPIKEVAX 2023-2024), when the patient developed low-grade fevers, dry cough, and dyspnea. A chest CT revealed extensive bilateral consolidation along with subpleural foci of GGOs. His rheumatologic workup was negative, and his infectious workup was notable only for positive Mycoplasma pneumoniae IgG, but negative IgM. Bronchoalveolar lavage showed no diffuse alveolar hemorrhage or eosinophilia, and transbronchial biopsy confirmed OP. His symptoms initially improved with corticosteroids, and he received 1 additional mRNA vaccine dose that correlated to worsening of disease (Date and vaccine brand were not provided).  His symptoms and radiographic abnormalities returned when corticosteroids were tapered, and he remained corticosteroid dependent. The outcome of the event was reported as recovering. The mentioned medical history remains as a confounder. The benefit-risk relationship of mRNA-1273.815 (SPIKEVAX 2023-2024) is not affected by this report.