she got Clostridium difficile infection and bleeding in feces; This spontaneous case was reported by a physician and describes the occurrence of CLOSTRIDIUM DIFFICILE INFECTION (she got Clostridium difficile infection and bleeding in feces) in an 83-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     The patient's past medical history included Gastrointestinal stromal tumor (gastrointestinal stromal tumor (GIST) which was diagnosed 5-6 months ago.) and Blood transfusion. Previously administered products included for Product used for unknown indication: FLU [INFLUENZA VACCINE] on 16-Aug-2021. Past adverse reactions to the above products included No adverse event with FLU [INFLUENZA VACCINE]. Concomitant products included VITAMINS NOS and PRAVASTATIN for an unknown indication.   On 13-Apr-2022, the patient received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form and first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced CLOSTRIDIUM DIFFICILE INFECTION (she got Clostridium difficile infection and bleeding in feces) (seriousness criterion medically significant). At the time of the report, CLOSTRIDIUM DIFFICILE INFECTION (she got Clostridium difficile infection and bleeding in feces) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   Treatment details included Blood Transfusion. On 16-May-2022 it was reported that patient had received her booster shot a month ago and that was her 4th shot of Moderna vaccine. She just had 4 units of transfusions, in other words, 2 pints out of the 14 that she normally had. Reporter wanted to know what that due to the effect of the last booster, was it be minimized or patient needed to take another booster. On 18-May-2022 caller mentioned that he was calling on be half of his wife, Patient had received 2 primary doses of the Moderna COVID-19 vaccine as well as 2 booster doses. She had not received any other vaccines close to receiving the Moderna vaccine. Patient had a pre-existing condition called gastrointestinal stromal tumor (GIST) which was diagnosed 5-6 months ago, her only problem was that she had GIST. Patient started experiencing bleeding in her feces for which she had to receive 2 units of Rh positive, type A blood. One week after this transfusion, patient continued to bleed in her feces and therefore had to receive 2 more unites of whole blood Rh positive, type A and type O. Caller hypothesized that prior to receiving the transfusions, patient had developed a Clostridium difficile infection. He told that this was not a reaction to the vaccine, but suspected that due to the C. diff infection, patient experienced a breach in her colon and therefore the bleeding. He told that his wife had no reaction to any doses of the Moderna vaccine, he also stated that she was generally a very healthy person. Company Comment: This spontaneous case concerns an 83-year-old female gender patient, with relevant medical history of gastrointestinal stromal tumor (GIST) diagnosed 5-6 months ago, has received 2 primary doses of the Moderna COVID-19 vaccine and 2 booster doses, who experienced the unexpected serious (medically significant) event of Clostridium difficile infection that occurred a month after the 4th dose of mRNA-1273 vaccine. Patient presented blood in stools for which 2 units of blood was transfused. And a week after, still with bleeding, another 2 units of blood was transfused. Clinical course and treatment details were not reported. The outcome of event was unknown. Elderly age of the patient and the medical history of gastrointestinal stromal tumor could be considered as risk factors. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event's seriousness was assessed based on medical judgement.; Sender's Comments: This spontaneous case concerns an 83-year-old female gender patient, with relevant medical history of gastrointestinal stromal tumor (GIST) diagnosed 5-6 months ago, has received 2 primary doses of the Moderna COVID-19 vaccine and 2 booster doses, who experienced the unexpected serious (medically significant) event of Clostridium difficile infection that occurred a month after the 4th dose of mRNA-1273 vaccine. Patient presented blood in stools for which 2 units of blood was transfused. And a week after, still with bleeding, another 2 units of blood was transfused. Clinical course and treatment details were not reported. The outcome of event was unknown. Elderly age of the patient and the medical history of gastrointestinal stromal tumor could be considered as risk factors. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event's seriousness was assessed based on medical judgement.