Focal Segmental Glomerulosclerosis recurrence; This literature-non-study case was reported in a literature article and describes the occurrence of FOCAL SEGMENTAL GLOMERULOSCLEROSIS (Focal Segmental Glomerulosclerosis recurrence) in a 21-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.       The patient's past medical history included Kidney transplant. Previously administered products included for Kidney transplant: Losartan (maintained normal allograft function with stable and low level proteinuria on losartan 12.5 mg/day); for Focal segmental glomerulosclerosis: Rituximab. Past adverse reactions to the above products included No adverse event with Losartan and Rituximab. Concurrent medical conditions included Focal segmental glomerulosclerosis (8 years status post deceased kidney transplant, and recurred early post-transplant).    On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced FOCAL SEGMENTAL GLOMERULOSCLEROSIS (Focal Segmental Glomerulosclerosis recurrence) (seriousness criterion medically significant). The patient was treated with METHYLPREDNISOLONE (intravenous) for Focal segmental glomerulosclerosis, at a dose of 1 gram for 3 days; RITUXIMAB for Focal segmental glomerulosclerosis, at a dose of 375 mg/m2 two times per week and PREDNISONE (oral) for Focal segmental glomerulosclerosis, at a dose of Taper. At the time of the report, FOCAL SEGMENTAL GLOMERULOSCLEROSIS (Focal Segmental Glomerulosclerosis recurrence) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Biopsy: abnormal (abnormal) Allograft biopsy revealed foot process effacement without definitive evidence of segmental sclerosis.. On an unknown date, Blood albumin: 4.8g/dl Routine labs 1 day prior to COVID 19 mRNA vaccine, 1.7 g/dl (Low) Thirty-one days after the second COVID 19 vaccine , routine labs were significant for nephrotic range proteinuria(hypoalbuminemia) and 3.5 g/dl During week 4 of plasmapheresis concurrent with prednisone taper. On an unknown date, Blood creatinine: 0.8 mg/dl Routine labs 1 day prior to COVID 19 mRNA vaccine, 1.3 mg/dl Thirty-one days after the second COVID 19 vaccine , routine labs were significant for nephrotic range proteinuria and 0.57 mg/dl During week 4 of plasmapheresis concurrent with prednisone taper. On an unknown date, Protein urine: 65 mg/dl Routine labs 1 day prior to COVID 19 mRNA vaccine and >2500 mg/dl Thirty-one days after the second COVID 19 vaccine , routine labs were significant for nephrotic range proteinuria. On an unknown date, SARS-CoV-2 test: negative (Negative) Infectious workup including viral studies for SARS-CoV-2 were negative.. On an unknown date, Urine output: decreased (Low) decreased urine output. On an unknown date, Urine protein/creatinine ratio: 0.42 mg/mg Routine labs 1 day prior to COVID 19 mRNA vaccine, >6.21 mg/mg Thirty-one days after the second COVID 19 vaccine , routine labs were significant for nephrotic range proteinuria and 0.55 mg/mg During week 4 of plasmapheresis concurrent with prednisone taper.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered FOCAL SEGMENTAL GLOMERULOSCLEROSIS (Focal Segmental Glomerulosclerosis recurrence) to be possibly related.    History was responded to plasmapheresis and Rituximab.  Patient remained asymptomatic until 2 days prior to labs when noted to have periorbital and lower extremity edema associated with decreased urine output.  During week 4 of plasmapheresis(PP) concurrent with prednisone taper, the patient appeared clinically well with noted improvement in labs. So weaned of PP and steroids.  Author concluded that although causality is not proven, the temporal relationship strongly suggests an association between the vaccine and the recurrence. Compared with prior reports, our patient presented somewhat later, ~1 month after dose #2 as compared to within 2 weeks after dose #1. Although the riskbenefit ratio of COVID vaccination for kidney transplant recipients remains favorable and vaccination is encouraged by national clinical guidelines, close monitoring after COVID vaccine for kidney transplant patients at risk for disease recurrence is warranted.  This Literature-Non-Study case concerns a 21 year-old, male patient with a history of Focal segmental glomerulosclerosis and Renal transplant, who experienced the serious unexpected event of Focal segmental glomerulosclerosis. The event occurred approximately 1 month after the second dose of mRNA-1273 vaccine. The rechallenge was not applicable, as the event was reported exclusively after the second dose. The event was considered related to the vaccine per the reporter's assessment. The medical history, of Focal segmental glomerulosclerosis and Renal transplant, remain as confounders. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 10-Nov-2021: Follow up received by safety on 11-Nov-2021 included an Email team with full text article and abstract and does not contain any new information.; Sender's Comments: This Literature-Non-Study case concerns a 21 year-old, male patient with a history of Focal segmental glomerulosclerosis and Renal transplant, who experienced the serious unexpected event of Focal segmental glomerulosclerosis. The event occurred approximately 1 month after the second dose of mRNA-1273 vaccine. The rechallenge was not applicable, as the event was reported exclusively after the second dose. The event was considered related to the vaccine per the reporter's assessment. The medical history, of Focal segmental glomerulosclerosis and Renal transplant, remain as confounders. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.