couldn't think straight; weakness,because they ended up in bed,; shaky; her arm was sore and went across her shoulder; This spontaneous case was reported by a consumer and describes the occurrence of MENTAL IMPAIRMENT (couldn't think straight) in a 73-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 029K20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Migraine (Since 30 years old.). Concomitant products included PARACETAMOL (TYLENOL [PARACETAMOL]) for Migraine.    On 06-Feb-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In 2021, the patient experienced MENTAL IMPAIRMENT (couldn't think straight) (seriousness criterion medically significant), ASTHENIA (weakness,because they ended up in bed,), TREMOR (shaky) and VACCINATION SITE PAIN (her arm was sore and went across her shoulder). At the time of the report, MENTAL IMPAIRMENT (couldn't think straight), ASTHENIA (weakness,because they ended up in bed,), TREMOR (shaky) and VACCINATION SITE PAIN (her arm was sore and went across her shoulder) outcome was unknown.            After the second and third dose, her arm was sore and went across her shoulder, but it didn't go up to the back of her head. She had bits of passing out. She had intense nausea that hit her stomach at first; it was weird. She didn't feel like throwing up. A strange feeling went up her stomach, but then it hit her head and felt like an explosion in her head. It was intense. It felt like her head was going to explode. Her vision was going black, and she felt like she was going to pass out. She felt weak and had to sit down. She stated she cannot drive like this because it happens so quickly. She was very weak and shaky in the morning. The patient stated she had brain fog, but she doesn't remember whether it started after the first or second dose. She couldn't think straight. Her thinking skills weren't as good. the brain fog has improved slowly, but not as she was before the first dose. Company comment: This case concerns a 73-year-old, female patient with no relevant medical history reported, who experienced the unexpected serious event of Mental impairment (reported as brain fog, among other), with concurrent asthenia, that occurred at an unknown day after the first or second dose of mRNA-1273 vaccine (the patient could not remember when it began). Mental impairment was also reported in relation with the booster dose, but it is not clearly stated if it had improved before the booster dose or if it was ongoing, thus the rechallenge is not applicable. She states the brain fog has improved slowly, but she is not back to what she was before the first dose. The patient also referred that It took almost 6 months to get over the experience, and when she received the third dose it was starting all over again, although the specific symptoms that reappeared are not detailed (except for pain in extremity). The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. Case was assessed as serious due to important medical event and medical judgement   This case was linked to MOD-2021-409978, MOD-2021-410013 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 15-Nov-2021: Significant Follow up included DOB added, serious event added.; Sender's Comments: This case concerns a 73-year-old, female patient with no relevant medical history reported, who experienced the unexpected serious event of Mental impairment (reported as brain fog, among other), with concurrent asthenia, that occurred at an unknown day after the first or second dose of mRNA-1273 vaccine (the patient could not remember when it began). Mental impairment was also reported in relation with the booster dose, but it is not clearly stated if it had improved before the booster dose or if it was ongoing, thus the rechallenge is not applicable. She states the brain fog has improved slowly, but she is not back to what she was before the first dose. The patient also referred that It took almost 6 months to get over the experience, and when she received the third dose it was starting all over again, although the specific symptoms that reappeared are not detailed (except for pain in extremity). The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. Case was assessed as serious due to important medical event and medical judgement.