Diet wise did feel ill/was not well; brain fog; don't think had the full effect of the vaccine and feel like it didn't work; This spontaneous case was reported by a patient and describes the occurrence of MALAISE (Diet wise did feel ill/was not well), FEELING ABNORMAL (brain fog) and VACCINATION FAILURE (don't think had the full effect of the vaccine and feel like it didn't work) in an adult male patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (batch no. 021H22A) for COVID-19 prophylaxis.     Concurrent medical conditions included Allergy to antibiotic (Amoxicillin).    On 07-Nov-2022, the patient received third dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) 1 dosage form. On an unknown date, the patient experienced MALAISE (Diet wise did feel ill/was not well), FEELING ABNORMAL (brain fog) and VACCINATION FAILURE (don't think had the full effect of the vaccine and feel like it didn't work). At the time of the report, MALAISE (Diet wise did feel ill/was not well), FEELING ABNORMAL (brain fog) and VACCINATION FAILURE (don't think had the full effect of the vaccine and feel like it didn't work) outcome was unknown.        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.   Concomitant medications were not reported.  The patient felt like that the patient did not have got the full effect of vaccine and things were not like 100 percent fine for the patient. The patient was curious to know whether the patient should have been informed more about following any diet, dietary restrictions or anything previously, so the patient did not continuously have like brain fog or any similar symptoms. The patient could definitely feel the difference when he ate fast food at restaurants or ate food that was cooked at the house. When he got the vaccine, it was normal at first and then the patient had a terrible experience. The patient had not been well since the second dose. Patient reported that he got the booster dose of vaccine on the right side, and the primary dose series on the left side and asked if that had anything to do with it or should he get another booster dose because the vaccine did not work or something. The patient was told that he was going to regret about taking the vaccine, and the patient thought that it was more of like an environmental thing that made it not work. Treatment medications were not reported.  Company Comment: This spontaneous case report concerns an adult male patient with no relevant medical history, who experienced non serious unexpected events of Feeling abnormal, Malaise and Vaccination failure. Reportedly, after administration of mRNA-1273.222 vaccine (as booster dose), on an unspecified date the patient was not well. He also stated that he did not think that he had the full effect of the vaccine and he felt like it didn't work, as stated. He also felt ill and he had brain fog and he was asking whether he should have been informed more about following any diet, or dietary restrictions. At the time of this report, the outcome of the events remained unknown and no additional details were disclosed. No further details were available for medical assessment. The benefit-risk relationship of mRNA-1273.222 vaccine is not affected by this report.   This case was linked to MOD-2023-708578 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 06-Feb-2023: Live significant follow up-patient information updated, vaccination date updated, narrative updated.; Sender's Comments: This spontaneous case report concerns an adult male patient with no relevant medical history, who experienced non serious unexpected events of Feeling abnormal, Malaise and Vaccination failure. Reportedly, after administration of mRNA-1273.222 vaccine (as booster dose), on an unspecified date the patient was not well. He also stated that he did not think that he had the full effect of the vaccine and he felt like it didn't work, as stated. He also felt ill and he had brain fog and he was asking whether he should have been informed more about following any diet, or dietary restrictions. At the time of this report, the outcome of the events remained unknown and no additional details were disclosed. No further details were available for medical assessment. The benefit-risk relationship of mRNA-1273.222 vaccine is not affected by this report.