Transient dermatomyositis-like reaction following COVID-19 messenger RNA vaccination; She had previously received a single dose of the Johnson & Johnson vaccine; This is a literature report for the following literature source(s):  A 50-year-old female patient received BNT162b2, BNT162b2 omi ba.4-5, as dose number unknown (booster), single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "pneumonia" (unspecified if ongoing), notes: 6 months prior; "mild ulcerative colitis" (unspecified if ongoing), notes: managed with dietary measures; "colonoscopy" (unspecified if ongoing). The patient's concomitant medications were not reported. Vaccination history included: Johnson & johnson vaccine (DOSE NUMBER UNKNOWN, SINGLE (without side effects)), for Covid-19 vaccination. The following information was reported: DERMATOMYOSITIS (medically significant), 2 weeks after the suspect product(s) administration, outcome "recovered", described as "Transient dermatomyositis-like reaction following COVID-19 messenger RNA vaccination"; INTERCHANGE OF VACCINE PRODUCTS (medically significant), outcome "unknown", described as "She had previously received a single dose of the Johnson & Johnson vaccine". Therapeutic measures were taken as a result of dermatomyositis. Clinical course: The patient with no known history of COVID-19 infection presented with myalgias, muscle weakness, and skin eruption beginning 2 weeks after her Pfizer/BioNTech BNT162b2 booster. She had previously received a single dose of the Johnson & Johnson vaccine without side effects. COVID-19 polymerase chain reaction(PCR) was negative at symptom onset. There was no associated weight loss, cough, ordysphagia. Medical history included a single pneumonia, 6 months prior as well as mild ulcer ativecolitis managed with dietary measures; colonoscopy and all other routine screenings were up to date. The patient was on no medications at symptom onset. Examination revealed erythematous lichenoid papules over the digits and elbows and abilateral violaceous eruption over the lateral aspect of the thighs, consistent with Gottron'spapules, Gottron's sign, and Holstersign,respectively. Examination also revealed violaceous psoriasiform erythema on scalp, but heliotrope eruptions, cuticular changes, and gross muscle weakness were absent. Workup revealed a creatine kinase(CK) [2700, antinuclear antibody (ANA) 1:160 with homogenous staining, and a negative limited myositis antibody panel, including Mi-2. Shave biopsy from the scalp demonstrated interface dermatitis with dermal mucinosis; shave biopsy from the right side of the second metacarpophalangeal joint similarly demonstrated interface dermatitis. Direct immunofluorescence for both sites revealed granularjunctional deposition of C3 with immunoglobulin M also present for the hand biopsy; IgA/IgG were negative for both the sites. Given the clinicopatho-logic features concerning for DM, the patient was treated with a prednisone taper from 40 mg per day to off over several weeks with brisk and full normalization of muscle enzymes. The skin eruptions, particularly over the thighs, were slower to resolve, lasting several months. At 4 months from initial presentation, the patient reported resolution of all symptoms, including her skin lesions off treatment with follow-up laboratory testings demonstrating normal CK and aldolase and negative myositis antibody panel, including Mi-2, MDA-5, TIF-1 gamma, and NXP-2.; Sender's Comments: Based on the information in the case report, a possible causal relationship between the events Dermatomyositis, Interchange of vaccine products and suspect product BNT162b2 cannot be completely excluded. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to Regulatory Authorities, Ethics Committees and Investigators, as appropriate.