chronic spontaneous urticaria; This literature-non-study case was reported in a literature article and describes the occurrence of CHRONIC SPONTANEOUS URTICARIA (chronic spontaneous urticaria) in a 34-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.   LITERATURE REFERENCE:      No Medical History information was reported.    On an unknown date, the patient received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced CHRONIC SPONTANEOUS URTICARIA (chronic spontaneous urticaria) (seriousness criterion medically significant). The patient was treated with DIPHENHYDRAMINE at a dose of 50 milligram every six hours; LORATADINE at an unspecified dose and frequency; PREDNISONE at a dose of 40 milligram once a day; PREDNISONE at a dose of 5 milligram once a day; FAMOTIDINE at an unspecified dose and frequency; CETIRIZINE HYDROCHLORIDE (CETRIZINE) at an unspecified dose and frequency and OMALIZUMAB at an unspecified dose and frequency. At the time of the report, CHRONIC SPONTANEOUS URTICARIA (chronic spontaneous urticaria) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Physical examination: Examination revealed mild periorbital edema, dermatographism, and diffuse urticaria of extremities and trunk. On an unknown date, Vital signs measurement: normal.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   No concomitant medications were reported.  Patient was presented with 1 day of diffuse urticaria and dermatographism unresponsive to loratadine and diphenhydramine. The patient reported no apparent allergic exposures and denied dyspnea, wheezing, emesis, or angioedema. Recent history was notable only for Moderna COVID-19 vaccine booster administered 10 days prior.   After allergist follow-up 3 days later, the patient was prescribed an extended steroid taper, cetirizine, famotidine, and diphenhydramine. At day 23 follow-up, the patient reported persistent symptoms on low-dose prednisone (5 mg daily) and antihistamines. At day 42 , the patient was diagnosed with chronic spontaneous urticaria and her allergist prescribed omalizumab.  Company comment: This is a literature non-study case concerning a 34 year-old, female patient with no relevant medical history who experienced the serious (due to medically significant) unexpected, adverse event of Chronic spontaneous urticaria. The event occurred approximately 9 days after the mRNA-1273 vaccine (dose number was not provided). The patient presented diffuse urticaria and dermatographism; she did not have apparent allergic exposures and denied dyspnea, wheezing, emesis, or angioedema. Vital signs were normal, and examination revealed mild periorbital edema, dermatographism, and diffuse urticaria of extremities and truns. The patient was prescribed diphenhydramine 50 mg every 6 hours and prednisone 40 mg daily. After allergist follow-up 3 days later, the patient was prescribed an extended steroid taper, cetirizine, famotidine, and diphenhydramine. At day 23 follow-up, the patient reported persistent symptoms on low-dose prednisone (5 mg daily) and antihistamines, and at day 42, the patient was diagnosed with chronic spontaneous urticaria and her allergist prescribed omalizumab. The outcome of the event was not provided. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 09-Mar-2023: Live follow up received by safety on 10-Mar-2023 has email with full text article and contains significant information. Literature information, laboratory data, product details, treatment medication and narrative were updated.