Hives really stinging and burning up to armpits, down to lower thigh and on neck and arm; Arm burning; Arm really itchy; Upper lip, side of nose, lower chin swollen; Lower chin hurts; Throat kind of scratchy; Allergic reaction; When drinking and eating food, something stuck on throat, like airpipe not smooth; Arm and legs had hives; Bump on scalp, getting bigger; Groggy; Something in throat, like choking; Left arm hurt; Left arm was swollen; Lower lip swollen; A spontaneous report was received from a consumer, a 49 year-old female patient, who received Moderna's COVID-19 Vaccine (mRNA-1273) and who experienced Allergic reaction, left arm hurt/pain in extremity, left arm was swollen/peripheral swelling, bump on scalp, getting bigger/mass, scalp bump itchy/pruritus, arm and legs had hives/urticaria, groggy/somnolence, something in throat, like choking/choking sensation, lower lip swollen/lip swelling, when drinking and eating food, something stuck on throat, like airpipe not smooth/foreign body in throat, backside hives/urticaria, upper lip, side of nose, lower chin swollen/swelling face, lower chin hurts/facial pain, throat kind of scratchy/throat irritation, arm really itchy/pruritis,arm really sting/pain, arm burning/burning sensation, stomach side, both full of big, patchy hives/urticaria, hives really stinging and burning up to armpits, down to lower thigh and on neck and arm/pain, and still has a lot of hives/urticaria.  The patient's medical history was not provided. Concomitant product use was not provided.   On, 10 Jan 2021, the patient received their first of two planned doses of mRNA-1273 (Batch number: 037K2DA). On 04 Feb 2021, a day prior to the onset of the events, the patient received the second of two planned doses of mRNA-1273 (Batch number: 015M20A) for COVID-19 infection prophylaxis.   On 05 Feb 2021, the patient's left arm was swollen and hurt. Around 6:00 a.m., she put her hand on her scalp, and she felt a bump. After 15 minutes, she touched the bump again and it was getting bigger and itchy. Beside that bump there was another bump, so she took diphenhydramine. At 9:30, she felt the bumps were spreading on her scalp. Then the patient saw that she had real hives on her arm. Thirty minutes later, she noticed her legs had a lot of hives too. A nurse told her it was an allergic reaction. She stated she knew herself and had never had an allergic reaction like this. She took 2 diphenhydramine and when she got home at 12:00 p.m., she felt groggy and fell asleep. When she woke up, there was something in her throat, like she was choking. Her lower lip was swollen. She had her husband take her to the emergency room (ER). They treated her with an intravenous (IV) line and some medication (unspecified). They administered an epinephrine shot, which helped. She was released at 11:00 p.m.  On 06 Feb 2021, the patient felt alright, but when she was drinking and eating food, something was stuck on her throat, like her airpipe was not smooth. She saw that on her backside, the hives flared up again. The patient went back to the emergency room to get shots and steroids (both unspecified). They prescribed her some medication and released her. After that, the hives were controllable.   On 07 Feb 2021, the patient woke up and her upper lip, side of her nose, and lower chin were swollen. She stated her chin hurt too. The patient's throat was kind of scratchy and she still had the hives. She went back to the ER, they gave her some shots (unspecified), and sent her home again. The patient stated she was very uncomfortable and that she'd never been sick and hadn't been to the hospital for a long time.   On 08 Feb 2021, the patient woke up and her arm was really itchy. Her arm was really stinging, burning, and swollen. She stated that her "stomach on her side part, both of them are really full of big, patchy hives". The hives were really stinging and burning. She reported that they went up to her armpits and down to her lower thigh. She said the worst was on her neck and arm. She couldn't tolerate it so she went back to the ER that night. The doctor gave her a shot of epinephrine, which helped a lot. She believes it eased the swelling and the pain.  On 09 Feb 2021, she still had a lot of hives and they were still was flaring up. She reported that she couldn't go to work, and she felt really uncomfortable. She stated that was the first time that she has had an allergic reaction from a shot and that she never has had an adverse reaction to any shot or any medication.  The patient received both scheduled doses of mRNA-1273 prior to the events; therefore, action taken with the drug in response to the events is not applicable.  The event, still has a lot of hives, was considered not resolved. The outcome of the events, Allergic reaction, left arm hurt, left arm was swollen, bump on scalp, getting bigger, scalp bump itchy, arm and legs had hives, groggy, something in throat, like choking, lower lip swollen, when drinking and eating food, something stuck on throat, like airpipe not smooth, backside hives, upper lip, side of nose, lower chin swollen, lower chin hurts, throat kind of scratchy, arm really itchy, arm really sting, arm burning, stomach side, both full of big, patchy hives, hives really stinging and burning up to armpits, down to lower thigh and on neck and arm, was considered unknown.; Reporter's Comments: This case concerns a 49 Y/O F with serious expected allergic reaction along with serious unexpected choking sensation, throat irritation, pain, and NS unexpected urticaria, pruritus, burning sensation, extremity pain, scalp mass, itchy scalp, face swelling lip swelling, facial pain, throat foreign body.  Event onset 27 days after first and 1 day after second dose mRNA-1273. Based on current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded.