Severe muscle weakness; Very weak couldnot really walk; She hasn't had clear thoughts for several years. It fired up her brain, she said "I have so much to think about ..i gotta think about some stuff; She was so weak she couldn't sit up.; Sharp pains in her side. She keeps saying her breast hurt off to side under her armpit; She is still very tired and kind of lethargic. She wants to stay in bed.; increase in brain activity; elevated temperature 102; All of a sudden, she starting vomiting. She hurled. It flew out of her body without any warning.; She is still very tired and kind of lethargic. She wants to stay in bed.; This spontaneous case was reported by a consumer and describes the occurrence of MUSCULAR WEAKNESS (Severe muscle weakness), GAIT INABILITY (Very weak couldnot really walk), THINKING ABNORMAL (She hasn't had clear thoughts for several years. It fired up her brain, she said "I have so much to think about ..i gotta think about some stuff), ASTHENIA (She was so weak she couldn't sit up.) and PAIN (Sharp pains in her side. She keeps saying her breast hurt off to side under her armpit) in a 91-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 044A21A and 006M20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Alzheimer's disease.   On 17-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 17-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 18-Mar-2021, the patient experienced MUSCULAR WEAKNESS (Severe muscle weakness), GAIT INABILITY (Very weak couldnot really walk), THINKING ABNORMAL (She hasn't had clear thoughts for several years. It fired up her brain, she said "I have so much to think about ..i gotta think about some stuff), ASTHENIA (She was so weak she couldn't sit up.), LETHARGY (She is still very tired and kind of lethargic. She wants to stay in bed.), THERAPEUTIC RESPONSE UNEXPECTED (increase in brain activity), PYREXIA (elevated temperature 102), VOMITING (All of a sudden, she starting vomiting. She hurled. It flew out of her body without any warning.) and FATIGUE (She is still very tired and kind of lethargic. She wants to stay in bed.). 18-Mar-2021, the patient experienced PAIN (Sharp pains in her side. She keeps saying her breast hurt off to side under her armpit). On 18-Mar-2021, PYREXIA (elevated temperature 102) and VOMITING (All of a sudden, she starting vomiting. She hurled. It flew out of her body without any warning.) had resolved. At the time of the report, MUSCULAR WEAKNESS (Severe muscle weakness), GAIT INABILITY (Very weak couldnot really walk), THINKING ABNORMAL (She hasn't had clear thoughts for several years. It fired up her brain, she said "I have so much to think about .i gotta think about some stuff), ASTHENIA (She was so weak she couldn't sit up.), PAIN (Sharp pains in her side. She keeps saying her breast hurt off to side under her armpit), LETHARGY (She is still very tired and kind of lethargic. She wants to stay in bed.), THERAPEUTIC RESPONSE UNEXPECTED (increase in brain activity) and FATIGUE (She is still very tired and kind of lethargic. She wants to stay in bed.) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 18-Mar-2021, Body temperature: high (High) 102.         No relevant concomitant medications were reported.   No treatment information was provided.    Action taken with mRNA-1273 in response to the events was not applicable.   This case was linked to MOD-2021-054304 (Patient Link).