hives from waist down to stomach down to toes; Inside of her leg, rash was very painful to touch/still feels a lot of pain inside of her legs; headache; very high fever; Rash became very dark and red. Inside of her leg, rash was very painful to touch, doctor termed it as cellulitis; also had chills; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of CELLULITIS (Rash became very dark and red. Inside of her leg, rash was very painful to touch, doctor termed it as cellulitis), URTICARIA (hives from waist down to stomach down to toes), PAIN IN EXTREMITY (Inside of her leg, rash was very painful to touch/still feels a lot of pain inside of her legs), CHILLS (also had chills), HEADACHE (headache) and PYREXIA (very high fever) in a 71-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 026A21A) for COVID-19 vaccination.     Concurrent medical conditions included Allergy (history of allergies so she never took flu-shots, pneumonia shots or shingles shots.).    On 05-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) .5 milliliter. On 05-Mar-2021, the patient experienced CELLULITIS (Rash became very dark and red. Inside of her leg, rash was very painful to touch, doctor termed it as cellulitis) (seriousness criteria hospitalization and medically significant), URTICARIA (hives from waist down to stomach down to toes) (seriousness criterion hospitalization), PAIN IN EXTREMITY (Inside of her leg, rash was very painful to touch/still feels a lot of pain inside of her legs) (seriousness criterion hospitalization), CHILLS (also had chills) (seriousness criterion hospitalization), HEADACHE (headache) (seriousness criteria hospitalization and medically significant) and PYREXIA (very high fever) (seriousness criterion hospitalization). The patient was hospitalized from 12-Mar-2021 to 17-Mar-2021 due to CHILLS, HEADACHE, PAIN IN EXTREMITY, PYREXIA and URTICARIA, and then on 12-Mar-2021 due to CELLULITIS. At the time of the report, CELLULITIS (Rash became very dark and red. Inside of her leg, rash was very painful to touch, doctor termed it as cellulitis), URTICARIA (hives from waist down to stomach down to toes), CHILLS (also had chills), HEADACHE (headache) and PYREXIA (very high fever) outcome was unknown and PAIN IN EXTREMITY (Inside of her leg, rash was very painful to touch/still feels a lot of pain inside of her legs) had not resolved.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.       Treatment medications included Keflex, unspecified medicines at hospital, and oxycodone.   Concomitant medications included unspecified thyroid medicine.  This case concerns a 71-year-old female hospitalized with serious unexpected events of cellulitis, urticaria, pain in extremity, fever, chills, and headache. Event onset the same day as first dose mRNA-1273. Treated with antibiotics. Events ongoing. 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.; Sender's Comments: This case concerns a 71-year-old female hospitalized with serious unexpected events of cellulitis, urticaria, pain in extremity, fever, chills, and headache. Event onset the same day as first dose mRNA-1273. Treated with antibiotics. Events ongoing. 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.