Bullous pemphigoid flare up; Bullous pemphigoid flare up; This literature-non-study case was reported in a literature article and describes the occurrence of PEMPHIGOID (Bullous pemphigoid flare up) and CONDITION AGGRAVATED (Bullous pemphigoid flare up) in a 69-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.     The patient's past medical history included Symptomatic COVID-19 (patient had symptomatic COVID-19, 4 months prior to vaccination). Previously administered products included for Erythrodermic psoriasis: Cyclosporine (cyclosporine 3 mg/kg divided into two daily doses). Past adverse reactions to the above products included No adverse reaction with Cyclosporine. Concurrent medical conditions included Bullous pemphigoid since 2018 and Erythrodermic psoriasis. Concomitant products included ADALIMUMAB from May 2019 to an unknown date for Erythrodermic psoriasis.    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 PEMPHIGOID (Bullous pemphigoid flare up) (seriousness criterion medically significant) and CONDITION AGGRAVATED (Bullous pemphigoid flare up) (seriousness criterion medically significant). The patient was treated with BETAMETHASONE DIPROPIONATE (AUGMENTED BETAMETHASONE DIPROPIONATE) at a dose of two to three times weekly. At the time of the report, PEMPHIGOID (Bullous pemphigoid flare up) and CONDITION AGGRAVATED (Bullous pemphigoid flare up) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Physical examination: Patient had few widely scattered crusted erosions and pink, scaly papules over upper thigh. On an unknown date, SARS-CoV-2 test: (Positive) patient had symptomatic COVID-19, 4 months prior to vaccination.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   Patient presented with scattered erosions 2 weeks after receiving his second dose of the Moderna mRNA-1273 COVID-19 vaccine. Initial diagnosis of bullous pemphigoid (BP) was in late 2018 by histopathology, including consistent Direct immunofluorescence (DIF), and was later confirmed with consistent Indirect immunofluorescence (IIF) IIF (2019) :>1:40,960 BMZ IgG, 1:10,240 and Enzyme-linked immunosorbent assay ELISA (2019); BP180, 15 units; BP230, 63 units for both BP180 and BP230 in early 2019.   Due to concomitant erythrodermic psoriasis, patient had been initially managed with cyclosporine and then transitioned to adalimumab for maintenance treatment in May 2019.  Patient was not on long-term treatment specifically directed against BP. The patient's symptoms gradually improved, no additional intervention was required. During this time, the patient continued with adalimumab injections.  Company comment: This literature non study case concerns a 69 years-old, male patient with medical history of Bullous pemphigoid since 2018 and Erythrodermic psoriasis, who experienced the unexpected serious (medically significant) event of bullous pemphigoid (condition aggravated). The event occurred approximately 2 weeks after the second dose of mRNA-1273. Reportedly, patient experienced bullous pemphigoid flare up manifested as few, widely scattered crusted erosions and pink, scaly papules on his extremities. Patient was not on long-term treatment specifically directed against bullous pemphigoid but was on adalimumab treatment for psoriasis. The patient's symptoms gradually improved with application of augmented betamethasone dipropionate 0.05% ointment two to three times weekly; no additional intervention was required. During this time, the patient continued with adalimumab injections. Underlying conditions are confounding factors for flare up as natural course of disease. The benefit-risk relationship of mRNA-1273 is not affected by this report.