she got some swelling under her left arm after receiving the 3rd dose of the Moderna COVID-19 vaccine; she was diagnosed with a type of leukemia in OCT2022; she got COVID on 27MAY2022. She thinks she had long COVID as she did not have an appetite after getting infected with COVID, up until early 2023; This spontaneous case was reported by a patient and describes the occurrence of LEUKAEMIA (she was diagnosed with a type of leukemia in OCT2022) in an 89-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 032H21A, 024M20A and 003A21A) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 09-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 09-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 26-Jan-2022, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 27-May-2022,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced POST-ACUTE COVID-19 SYNDROME (she got COVID on 27MAY2022. She thinks she had long COVID as she did not have an appetite after getting infected with COVID, up until early 2023). In October 2022, the patient experienced LEUKAEMIA (she was diagnosed with a type of leukemia in OCT2022) (seriousness criterion medically significant). On an unknown date, the patient experienced PERIPHERAL SWELLING (she got some swelling under her left arm after receiving the 3rd dose of the Moderna COVID-19 vaccine). At the time of the report, LEUKAEMIA (she was diagnosed with a type of leukemia in OCT2022) and POST-ACUTE COVID-19 SYNDROME (she got COVID on 27MAY2022. She thinks she had long COVID as she did not have an appetite after getting infected with COVID, up until early 2023) outcome was unknown and PERIPHERAL SWELLING (she got some swelling under her left arm after receiving the 3rd dose of the Moderna COVID-19 vaccine) had not resolved.            Concomitant product use was not provided by the reporter.  It was reported that patient was supposed to get another booster dose in the latter part of 2022, but she forgot about it and never received one. She did not know if she had received the monovalent or bivalent COVID-19 vaccine for her last dose. She said that she was going to Alaska for a wedding in Aug-2023 and she would like to get her booster shot before that. She wanted to know if the Moderna COVID-19 booster shot was still free and if she should received it at this time. She went to her doctor regarding the swelling and was told that they would keep a watch on it. She was not sure but thought that some swelling might still be there.   Treatment information was not provided.  Company comment.  This spontaneous case concerns an 89  year  old female patient, with no medical history reported, who experienced the unexpected, serious (medically significant) event of leukaemia, which occurred approximately 9 months after a dose of mRNA  1273 original vaccine, third dose of her COVID  19 immunization schedules; the patient previously had 2 doses of mRNA - 1273 COVID  19 vaccines. The report stated that the patient was diagnosed with a type of leukemia in October 2022. No further clinical details were provided for medical reviewing. The benefit-risk relationship of mRNA  1273 original vaccine is not affected by this report.