Severe reaction; Itching; Redness; Softball-size rash on the arm (described as started small, then got bigger, and by 20Mar2021 it was huge); Threw up non stop for 3 days/ was throwing up; Nausea; Low grade fever (100); Sore arm at injection site; Huge red knot, hot to touch; Huge, red knot on his arm; This spontaneous case was reported by a consumer and describes the occurrence of VACCINATION SITE INDURATION (Huge, red knot on his arm), VACCINATION COMPLICATION (Severe reaction), VACCINATION SITE PRURITUS (Itching), VACCINATION SITE ERYTHEMA (Redness) and VACCINATION SITE WARMTH (Huge red knot, hot to touch) in a 36-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 026A21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Cholesterol, Blood pressure high and Mental handicap NOS (Not able to read or write). Concomitant products included ATENOLOL from 2019 to an unknown date for Blood pressure high, PRAVASTATIN from 2019 to an unknown date for Cholesterol high.    On 16-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) .5 ml. In March 2021, the patient experienced VACCINATION SITE INDURATION (Huge, red knot on his arm), VACCINATION SITE WARMTH (Huge red knot, hot to touch), VACCINATION SITE PAIN (Sore arm at injection site) and PYREXIA (Low grade fever (100)). On 16-Mar-2021, the patient experienced VACCINATION SITE RASH (Softball-size rash on the arm (described as started small, then got bigger, and by 20Mar2021 it was huge)), VOMITING (Threw up non stop for 3 days/ was throwing up) and NAUSEA (Nausea). On an unknown date, the patient experienced VACCINATION COMPLICATION (Severe reaction), VACCINATION SITE PRURITUS (Itching) and VACCINATION SITE ERYTHEMA (Redness). The patient was treated with ONDANSETRON (ZOFRAN [ONDANSETRON]) for Adverse event, at a dose of UNK dosage form. In March 2021, VACCINATION SITE RASH (Softball-size rash on the arm (described as started small, then got bigger, and by 20Mar2021 it was huge)) had resolved. On 19-Mar-2021, VOMITING (Threw up non stop for 3 days/ was throwing up) and NAUSEA (Nausea) had resolved. At the time of the report, VACCINATION SITE INDURATION (Huge, red knot on his arm), VACCINATION SITE WARMTH (Huge red knot, hot to touch), VACCINATION SITE PAIN (Sore arm at injection site) and PYREXIA (Low grade fever (100)) had resolved and VACCINATION COMPLICATION (Severe reaction), VACCINATION SITE PRURITUS (Itching) and VACCINATION SITE ERYTHEMA (Redness) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Body temperature: 100 (High) Low grade fever- 100.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.    This case was linked to MOD-2021-078048 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 09-Aug-2021: Follow up received and added Newevents. On 09-Aug-2021: Follow up received and added patient demographics, medical history, lab data, new events and updated concomitant dose description. On 10-Aug-2021: Follow up received and it contains non significant information. Reporter sent pictures of red knot.