itching all over; rash all over her body; she had a red square where she got the shot in the left arm.; might be allergic to the new vaccine; Urticaria (itchy rash/hives); This spontaneous case was reported by a patient and describes the occurrence of PRURITUS (itching all over), DRUG HYPERSENSITIVITY (might be allergic to the new vaccine), URTICARIA (Urticaria (itchy rash/hives)), RASH (rash all over her body) and INJECTION SITE ERYTHEMA (she had a red square where she got the shot in the left arm.) in a 70-year-old female patient who received mRNA-1273.815 (SPIKEVAX 2023-2024) (batch no. ASKU) for COVID-19 prophylaxis.     Patient did not report any medical history or condition.     On 19-Sep-2023, the patient received sixth dose of mRNA-1273.815 (SPIKEVAX 2023-2024) (unknown route) 1 dosage form. In September 2023, the patient experienced DRUG HYPERSENSITIVITY (might be allergic to the new vaccine), URTICARIA (Urticaria (itchy rash/hives)) and INJECTION SITE ERYTHEMA (she had a red square where she got the shot in the left arm.). On 22-Sep-2023,  after starting mRNA-1273.815 (SPIKEVAX 2023-2024), the patient experienced PRURITUS (itching all over) and RASH (rash all over her body). The patient was treated with HYDROCORTISONE at an unspecified dose and frequency. At the time of the report, PRURITUS (itching all over) and RASH (rash all over her body) had not resolved and DRUG HYPERSENSITIVITY (might be allergic to the new vaccine), URTICARIA (Urticaria (itchy rash/hives)) and INJECTION SITE ERYTHEMA (she had a red square where she got the shot in the left arm.) outcome was unknown.        For mRNA-1273.815 (SPIKEVAX 2023-2024) (Unknown), the reporter did not provide any causality assessments.   No concomitant medications were reported.  Patient stated she got the COVID-19 vaccine, the 6th dose on 19Sep2023. A few days later she had a red square where she got the shot in the left arm. She has a rash all over her body. She did some research, and it looked similar to the picture when she searched for COVID vaccine side effects. She has always taken Moderna vaccine, and this is her first time having a reaction. Since that date, she has been to the emergency room 3 times. Each time was a different result from each doctor. The 1st time they told her she had a topical rash. The 2nd time they told her she had a follicle rash. She stated each time they gave her oral medication and steroid. The 3rd time she went to the Doctor, she was told, they don't know what is wrong with the rash and they are not familiar with rash due to the vaccine. They gave her an injection and some medicine. As of right now she is itching all over. She can't get rid of the rash, and it has been 2 weeks. She tried oatmeal bath and liquid soak bath for irritation, and she was not getting any better. She stated she had spent a fortune in emergency room and soak bath. She was not sure. She does not know what changed but she believed she might be allergic to the new vaccine. She been taking 1% hydrocortisone over the counter. She does not know why this was happening.   No treatment medications were provided.   This case was linked to US-MODERNATX, INC.-MOD-2021-023142 (E2B Linked Report).; Sender's Comments:  US-MODERNATX, INC.-MOD-2021-023142:Monovalent Dose