slight echomosis in her left arm/echomosis started just below the deltoid muscle where the injection was given/Echomosis spread to her forearm; left arm continued to swell / Thursday morning there was immense swelling in her left arm/Left arm was three times its normal size; Interchange of vaccine products; Revaccination with different COVID-19 vaccine; had some pain in her left arm for two days; This spontaneous case was reported by a physician and describes the occurrence of INJECTION SITE HAEMORRHAGE (slight echomosis in her left arm/echomosis started just below the deltoid muscle where the injection was given/Echomosis spread to her forearm) and VACCINATION SITE SWELLING (left arm continued to swell / Thursday morning there was immense swelling in her left arm/Left arm was three times its normal size) in a 90-year-old female patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Previously administered products included for COVID-19 immunization: Pfizer covid-19 vaccine (Primary Series). Past adverse reactions to the above products included No adverse event with Pfizer covid-19 vaccine. Concurrent medical conditions included Myeloid dysplasia, Myasthenia gravis and Macular degeneration. Concomitant products included PYRIDOSTIGMINE and LOSARTAN for an unknown indication.    On 14-Oct-2022, the patient received fifth dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) 1 dosage form. In October 2022, the patient experienced INJECTION SITE HAEMORRHAGE (slight echomosis in her left arm/echomosis started just below the deltoid muscle where the injection was given/Echomosis spread to her forearm) (seriousness criterion hospitalization), VACCINATION SITE SWELLING (left arm continued to swell / Thursday morning there was immense swelling in her left arm/Left arm was three times its normal size) (seriousness criterion hospitalization) and VACCINATION SITE PAIN (had some pain in her left arm for two days). On an unknown date, the patient experienced INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine). The patient was hospitalized on 21-Oct-2022 due to INJECTION SITE HAEMORRHAGE and VACCINATION SITE SWELLING. In October 2022, VACCINATION SITE PAIN (had some pain in her left arm for two days) had resolved. At the time of the report, INJECTION SITE HAEMORRHAGE (slight echomosis in her left arm/echomosis started just below the deltoid muscle where the injection was given/Echomosis spread to her forearm), VACCINATION SITE SWELLING (left arm continued to swell / Thursday morning there was immense swelling in her left arm/Left arm was three times its normal size), INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 21-Oct-2022, Blood culture: no infection.     For mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (Unknown), the reporter did not provide any causality assessments.   The patient was received her first Moderna booster dose last fall and had a slight sore left arm. Lot number and expiration date was not known and received her second booster Moderna booster dose on 20-Mar-2022, lot number and expiration date were not known. The patient did not have any adverse reactions to her second booster dose. After receiving bivalent booster dose the patient had some pain in her left arm for two days. Then the patient developed a slight echomosis in her left arm. The echomosis started just below the deltoid muscle where the injection was given. The left arm continued to swell. On Thursday morning there was immense swelling in patient's left arm. Left arm was three times its normal size. Echomosis spread to patient's forearm. Patient went to Urgent Care and was taken to the Emergency room via ambulance. Patient was admitted to the hospital for observation. No treatment medications were reported.   This case was linked to MOD-2022-662521 (Patient Link).  Company comment: This spontaneous case concerns a 90-year-old female patient with relevant concurrent condition of myelodysplastic syndrome, who experienced serious (hospitalization) unexpected events of injection site haemorrhage and vaccination site swelling.  The events started occurring several days after the 5th, bivalent booster dose of the mRNA-1273.222.  Initially following vaccination, the patient developed some pain in the left arm which lasted for 2 days. Three days after the booster dose, the patient developed ecchymosis in her left arm, just below the deltoid muscle area, that further progressed to her forearm in the following days. Additionally, swelling of arm worsened to the point where it was three times larger than the normal size. The patient was hospitalized for observation. The patient's myelodysplastic syndrome and advanced age are possible confounders, as it is known that patient's with myelodysplasia have an increased tendency to bleed and bruise. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This spontaneous case concerns a 90-year-old female patient with relevant concurrent condition of myelodysplastic syndrome, who experienced serious (hospitalization) unexpected events of injection site haemorrhage and vaccination site swelling.  The events started occurring several days after the 5th, bivalent booster dose of the mRNA-1273.222.  Initially following vaccination, the patient developed some pain in the left arm which lasted for 2 days. Three days after the booster dose, the patient developed ecchymosis in her left arm, just below the deltoid muscle area, that further progressed to her forearm in the following days. Additionally, swelling of arm worsened to the point where it was three times larger than the normal size. The patient was hospitalized for observation. The patient's myelodysplastic syndrome and advanced age are possible confounders, as it is known that patient's with myelodysplasia have an increased tendency to bleed and bruise. The benefit-risk relationship of mRNA-1273 is not affected by this report.