I had anaphylaxis; palpitations; I felt my throat closing; I had trouble breathing; I slept for 3 days; arm pain for 3-4 days; fever; fatigue - I slept for 3 days; chills; This spontaneous case was reported by a consumer and describes the occurrence of ANAPHYLACTIC REACTION (I had anaphylaxis) in a 26-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 028L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Asthma.    On 25-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 25-Jan-2021, the patient experienced ANAPHYLACTIC REACTION (I had anaphylaxis) (seriousness criterion medically significant), PALPITATIONS (palpitations), THROAT TIGHTNESS (I felt my throat closing), DYSPNOEA (I had trouble breathing), HYPERSOMNIA (I slept for 3 days), INJECTION SITE PAIN (arm pain for 3-4 days), PYREXIA (fever), FATIGUE (fatigue - I slept for 3 days) and CHILLS (chills). The patient was treated with DIPHENHYDRAMINE HYDROCHLORIDE (BENADRYL [DIPHENHYDRAMINE HYDROCHLORIDE]) on 25-Jan-2021 at a dose of 25 milligram and IBUPROFEN (ADVIL [IBUPROFEN]) at an unspecified dose and frequency. At the time of the report, ANAPHYLACTIC REACTION (I had anaphylaxis), PALPITATIONS (palpitations), THROAT TIGHTNESS (I felt my throat closing), DYSPNOEA (I had trouble breathing), HYPERSOMNIA (I slept for 3 days), INJECTION SITE PAIN (arm pain for 3-4 days), PYREXIA (fever), FATIGUE (fatigue - I slept for 3 days) and CHILLS (chills) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Body temperature: increased (High) increased.     mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosing remained unchanged.       Patient took inhaler with her that day. Concomitant medications was not reported. The patient reported: 25Jan2021: I got the 1st dose of the Moderna Covid-19 vaccine. That same day, about 20 minutes after the injection, I had anaphylaxis. I felt my throat closing & I had trouble breathing. I took Benadryl 25mg. I had a fever, chills, arm pain for 3-4 days, fatigue - I slept for 3 days, & had palpitations. I took my inhaler with me that day.  Company comment: This case concerns a 26-year-old female patient with a medical history of asthma, who experienced the expected, serious (medically significant) event of anaphylaxis. The event occurred approximately 20 minutes after the first dose of mRNA-1273. The rechallenge was unknown since information about the outcome of events has not been provided, even though the patient reports that she experienced similar events after dose 2. The medical history of asthma is a confounder for throat tightness and dyspnoea, which are the symptoms described as "anaphylaxis". According to the Brighton collaboration criteria, there is insufficient evidence to meet any of levels of diagnostic certainty. The benefit-risk relationship of mRNA-1273 is not affected by this report.   This case was linked to MOD-2021-403814, MOD-2021-403695 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 02-Dec-2021: follow-up received it contains no new information.; Sender's Comments: This case concerns a 26-year-old female patient with a medical history of asthma, who experienced the expected, serious (medically significant) event of anaphylaxis. The event occurred approximately 20 minutes after the first dose of mRNA-1273. The rechallenge was unknown since information about the outcome of events has not been provided, even though the patient reports that she experienced similar events after dose 2. The medical history of asthma is a confounder for throat tightness and dyspnoea, which are the symptoms described as "anaphylaxis". According to the Brighton collaboration criteria, there is insufficient evidence to meet any of levels of diagnostic certainty. The benefit-risk relationship of mRNA-1273 is not affected by this report.