Oral Chronic Graft-versus-Host Disease; This literature-non-study case was reported in a literature article and describes the occurrence of CHRONIC GRAFT VERSUS HOST DISEASE ORAL (Oral Chronic Graft-versus-Host Disease) in a 70-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.   LITERATURE REFERENCE:     The patient's past medical history included Graft versus host disease oral in February 2021 and Allogeneic peripheral hematopoietic stem cell transplant (20 months prior). Concurrent medical conditions included Acute myeloid leukaemia since June 2019 and Myelofibrosis since June 2019. Concomitant products included TACROLIMUS for an unknown indication.    On 16-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In February 2021, the patient experienced CHRONIC GRAFT VERSUS HOST DISEASE ORAL (Oral Chronic Graft-versus-Host Disease) (seriousness criterion medically significant). At the time of the report, CHRONIC GRAFT VERSUS HOST DISEASE ORAL (Oral Chronic Graft-versus-Host Disease) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 09-Mar-2021, Oral cavity examination: examination revealed prominent white lichenoid lesions.. On 24-Mar-2021, Oral cavity examination: improvement in oral GVHD.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered CHRONIC GRAFT VERSUS HOST DISEASE ORAL (Oral Chronic Graft-versus-Host Disease) to be related.    Treatment medications were not reported clearly.  Patient did well post-HCT with no acute or cGVHD. He was on gradual tapering of tacrolimus since October 2020 and never had any exacerbation of GVHD. In early February 2021, he had oral changes consistent with mild oral GVHD. He was advised to resume steroid rinses and halted any further taper of the tacrolimus.  On March 09, 2021, he presented with oral sensitivity, and examination revealed prominent white lichenoid lesions. As a result, tacrolimus dosage was increased, and oral steroid rinses were continued. At his subsequent visit on March 24, 2021, oral examination showed improvement in oral GVHD.  Company Comment: This is a literature non-study case concerning a 70-year-old male patient, who underwent hematopoietic stem cell transplant (HCT) from an unrelated donor for secondary acute myeloid leukaemia from prior myelofibrosis in June 2019. He did well post-HCT with no acute or chronic graft versus host disease (GVHD). Patient experienced unexpected and serious (due to medically significant) event of Chronic graft versus host disease oral, which occurred after the first dose of mRNA-1273 vaccine. As reported, the patient was on gradual tapering of tacrolimus since October 2020 and never had any exacerbation of GVHD. When seen in early February 2021, he had oral changes consistent with mild oral GVHD. He was advised to resume steroid rinses and halted any further taper of the tacrolimus. After a couple of weeks, he did not report any worsening of the oral lesions. However, on March 09, 2021, he presented with oral sensitivity, and examination revealed prominent white lichenoid lesions 1 month following the first dose of mRNA-1273 vaccine on February 16, 2021. As a result, tacrolimus dosage was increased, and oral steroid rinses were continued. At his subsequent visit on March 24, 2021, oral examination showed improvement in oral GVHD. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this.