Endothelial graft rejection; decreased vision; This literature-non-study case was reported in a literature article and describes the occurrence of TRANSPLANT REJECTION (Endothelial graft rejection) in a 74-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.   The patient's past medical history included Keratoplasty.   On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced TRANSPLANT REJECTION (Endothelial graft rejection) (seriousness criterion medically significant) and VISUAL IMPAIRMENT (decreased vision). The patient was treated with PREDNISOLONE ACETATE for Cystoid macular edema, at a dose of UNK UNK, q2h; KETOROLAC for Cystoid macular edema, at an unspecified dose and frequency and FLUOROMETHOLONE for Cystoid macular edema, at a dose of UNK UNK, qd. At the time of the report, TRANSPLANT REJECTION (Endothelial graft rejection) was resolving and VISUAL IMPAIRMENT (decreased vision) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood immunoglobulin G: negative (Negative) negative. On an unknown date, Corneal pachymetry: increased (abnormal) the central corneal thickness (CCT) had increased to 743 um, (cct of 705 um) with resolution of descemet membra (abnormal) (CCT of 705 um) with resolution of Descemet membrane folds and improved (abnormal) improvement of CCT to 655 mm.. On an unknown date, Ophthalmological examination: abnormal (abnormal) At the 3-month postoperative visit, he was found to have mild cystoid macular edema (CME) while maintaining a clear cornea.. On an unknown date, Slit-lamp examination: examination revealed an endothelial (abnormal) Slitlamp examination revealed an endothelial rejection (Khodadoust) line in the superior aspect of the Descemet membrane endothelial keratoplasty (DMEK) disk accompanied by microcystic epithelial and stromal edema Descemet membrane folds, and keratic precipitates (KPs. On an unknown date, Visual acuity tests: improving Improving to 20/25 within 6 weeks with excellent corneal clarity., normal (normal) By the 5-month postoperative visit it restored, abnormal (abnormal) BCVA was reduced to 20/60 and improved Three weeks after the second vaccine and 5 weeks after initial presentation of rejection, BCVA improved to 20/40, with near resolution of the endothelial rejection line.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered TRANSPLANT REJECTION (Endothelial graft rejection) and VISUAL IMPAIRMENT (decreased vision) to be possibly related.    This case concern 1 out of 4 patient with prior keratoplasty developed presumed immunologic rejection after the mRNA-1273 vaccination for coronavirus 2 (SARS-CoV-2). In this case the patient had received Descemet membrane endothelial keratoplasty 6 months ago and presented with endothelial graft rejection 3 weeks after the first vaccine dose. The endothelial rejection line appeared fainter with improvement in visual acuity and corneal edema 5 weeks after diagnosis.   Topical prednisolone acetate 1% every 2 hours was immediately initiated. Within 2 days, the stromal edema had reduced (CCT of 705 mm) with resolution of Descemet membrane folds.  These cases suggest acute corneal endothelial rejection may occur soon after either dose of the COVID-19 mRNA vaccine. Prompt initiation of aggressive topical steroid therapy may result in complete resolution of clinical signs and symptoms. Further studies are needed to elucidate the causal mechanism of corneal graft rejection after COVID-19 vaccination.  Company Comment: This literature review case concerns a 74 year old male with a history of corneal transplant who experienced the serious unlisted event of Transplant rejection approximately 3 weeks after the first dose of mRNA-1273. Re-challenge is negative as the event did not recur after the second dose with prophylactic treatment. Benefit-risk relationship of mRNA-1273 is not affected by this report.   This case was linked to MOD-2021-353544, MOD-2021-353542, MOD-2021-353543 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 13-Oct-2021: Follow up received by safety on 14-Oct-2021 has with a regulatory authority and contain  new information about patient identifiers.; Sender's Comments: This literature review case concerns a 74 year old male with a history of corneal transplant who experienced the serious unlisted event of Transplant rejection approximately 3 weeks after the first dose of mRNA-1273. Re-challenge is negative as the event did not recur after the second dose with prophylactic treatment. Benefit-risk relationship of mRNA-1273 is not affected by this report.