Immediate hypersensitivity reaction; Interchange of vaccine products; Revaccination with different Covid19 vaccine; This literature-non-study case was reported in a literature article and describes the occurrence of TYPE I HYPERSENSITIVITY (Immediate hypersensitivity reaction) in a 24-year-old female patient who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.   Concurrent medical conditions included Asthma and Allergic rhinitis. Concomitant products included TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for COVID-19 prophylaxis.    On an unknown date, the patient received first dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, the patient experienced TYPE I HYPERSENSITIVITY (Immediate hypersensitivity reaction) (seriousness criteria medically significant and life threatening). an unknown date, the patient experienced INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different Covid19 vaccine). The patient was treated with EPINEPHRINE for Immediate hypersensitivity reaction, at an unspecified dose and frequency; DIPHENHYDRAMINE for Immediate hypersensitivity reaction, at an unspecified dose and frequency and METHYLPREDNISOLONE for Immediate hypersensitivity reaction, at an unspecified dose and frequency. At the time of the report, TYPE I HYPERSENSITIVITY (Immediate hypersensitivity reaction), INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different Covid19 vaccine) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, SARS-CoV-2 antibody test: 21,513 arbitrary unit per millilitre and 7657.3 arbitrary unit per millilitre. On an unknown date, Tryptase: 4.3 microgram per litre.     The action taken with mRNA-1273 (Spikevax) (Unknown) was unknown.   For mRNA-1273 (Spikevax) (Unknown), the reporter considered TYPE I HYPERSENSITIVITY (Immediate hypersensitivity reaction) to be related. No further causality assessments were provided for INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different Covid19 vaccine).    No concomitant medications were reported. Patient did not have history of anaphylaxis, allergy to vaccine and COVID-19 infection. Patient experience hives, throat closing sensation, severe tongue swelling within 25 minutes after first dose and. Vaccine excipient test was not done. Patient received treatment for Management of reaction to the first dose in ICU. Patient received the second dose of vaccine in incremental doses at 30-minute intervals to a cumulative dose of 0.3 ml, Patient was pre-medicated with a second-generation H1 antihistamine on the day of vaccination, and patient was observed for 1 hour after the final vaccine dose.  COVID-19 spike antibody levels were measured at least 2 weeks after the procedure. Cumulative time for second dose was reported as 3 hours, It was reported that 0.03, 0.06, 0.06, 0.06, 0.09 mL of sequential dose of vaccine was administered to complete a cumulative dose of 0.3 mL, reactions during graded dosing were none.   This case was linked to US-MODERNATX, INC.-MOD-2022-655503, US-MODERNATX, INC.-MOD-2022-655521, US-MODERNATX, INC.-MOD-2022-655522 (Linked Report).  This literature-non-study case concerns a 24-year-old female patient with medical history of Asthma and Allergic rhinitis, who experienced serious (medically significant and life-threatening) unexpected event of Type I hypersensitivity. Reportedly, 25 minutes after the patient had received the the first dose of the mRNA-1273 vaccine, she developed hives, throat closing sensation and severe tongue swelling. The patient received treatment with epinephrine, diphenhydramine and methylprednisolone in the intensive care unit. It was not specified whether the patient stayed in the intensive care unit for more than 24 hours. Interchange of vaccine products and COVID-19 immunisation (revaccination with different COVID-19 vaccine) are also considered in this specific case report since the patient had received Pfizer COVID-19 vaccine as her second dose in incremental doses at 30-minute intervals to a cumulative dose of 0.3 mL. The patient was pre-medicated with a second-generation H1 antihistamine on the day of vaccination and was observed for 1 hour after the final vaccine dose and did not develop any symptoms of hypersensitivity. The patient's underlying medical history remains a confounder as it speaks in favor of the patient's susceptibility to allergies. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.  Most recent FOLLOW-UP information incorporated above includes: On 06-Oct-2022: Live Follow up received by safety on 06-Oct-2022 has email with full text article received and contains significant information. Reporter information, literature information, laboratory data, product and event details updated.; Sender's Comments: This literature-non-study case concerns a 24-year-old female patient with medical history of Asthma and Allergic rhinitis, who experienced serious (medically significant and life-threatening) unexpected event of Type I hypersensitivity. Reportedly, 25 minutes after the patient had received the the first dose of the mRNA-1273 vaccine, she developed hives, throat closing sensation and severe tongue swelling. The patient received treatment with epinephrine, diphenhydramine and methylprednisolone in the intensive care unit. It was not specified whether the patient stayed in the intensive care unit for more than 24 hours. Interchange of vaccine products and COVID-19 immunisation (revaccination with different COVID-19 vaccine) are also considered in this specific case report since the patient had received Pfizer COVID-19 vaccine as her second dose in incremental doses at 30-minute intervals to a cumulative dose of 0.3 mL. The patient was pre-medicated with a second-generation H1 antihistamine on the day of vaccination and was observed for 1 hour after the final vaccine dose and did not develop any symptoms of hypersensitivity. The patient's underlying medical history remains a confounder as it speaks in favor of the patient's susceptibility to allergies. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. US-MODERNATX, INC.-MOD-2022-655503:29 yr old female US-MODERNATX, INC.-MOD-2022-655521:33 yr old female US-MODERNATX, INC.-MOD-2022-655522:35 yr old female