not being able to sleep at night; It was affecting her on the side of injection; She had right leg paralysis and severe problem ever since, unable to walk, had to limp; Inflammation of the muscle/very painful; Both legs felt like they were on fire; Bilat leg pain; This spontaneous case was reported by a consumer and describes the occurrence of MONOPLEGIA (She had right leg paralysis and severe problem ever since, unable to walk, had to limp) in a 50-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Allergy. Concomitant products included LORATADINE, PSEUDOEPHEDRINE SULFATE (CLARITIN-D) for Allergy.   On 24-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 21-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 21-Apr-2021,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced PAIN IN EXTREMITY (Bilat leg pain). On 21-Apr-2021 at 6:00 PM, the patient experienced MONOPLEGIA (She had right leg paralysis and severe problem ever since, unable to walk, had to limp) (seriousness criterion medically significant), MYOSITIS (Inflammation of the muscle/very painful) and LIMB DISCOMFORT (Both legs felt like they were on fire). On an unknown date, the patient experienced INSOMNIA (not being able to sleep at night) and VACCINATION SITE DISCOMFORT (It was affecting her on the side of injection). The patient was treated with Manual therapy (Massage therapy and Muscle rubs) for Myositis and Physical therapy (Massage and Acupuncture) for Pain in extremity. At the time of the report, MONOPLEGIA (She had right leg paralysis and severe problem ever since, unable to walk, had to limp), MYOSITIS (Inflammation of the muscle/very painful) and PAIN IN EXTREMITY (Bilat leg pain) had not resolved and LIMB DISCOMFORT (Both legs felt like they were on fire), INSOMNIA (not being able to sleep at night) and VACCINATION SITE DISCOMFORT (It was affecting her on the side of injection) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood creatine phosphokinase: normal (normal) normal. On an unknown date, Blood test: normal (normal) Normal. On an unknown date, C-reactive protein: normal (normal) normal. On an unknown date, Red blood cell sedimentation rate normal: normal (normal) normal.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   She had right leg paralysis and severe problem ever since. It had affected her on the side of injection. The vaccine was administered on the right-sided arm. For the second dose, she had her shot in the morning and by 6pm, both legs felt like they were on fire. Her right leg muscle was stone and paralyzed and she could not move without assistance from her husband. She had consulted a doctor and the diagnosis was inflammation of the muscle. She had to pay for massage therapy out from her own pocket to move the muscles for seven months. It helped a little. She was still unable to walk as she had to limp and it was still very painful .She spent several months not being able to sleep at night. Doctor had advised her to take tylenol if needed or else not to take. She had applied muscle rubs. It was terrible. No hospitalization. It was reported that patient presented on 13 May 2021 with right more than left leg pain that seemed to be muscular or myofascial in nature, lab test were normal. Patient showed improvement with physical therapy, massage and acupuncture. Company Comment: This case concerns a 50-year-old, female patient with relevant medical history of allergy who experienced the unexpected event of monoplegia (IME). The event occurred the same day after the second dose of mRNA-1273. The rechallenge was not applicable since the event happened after the second dose. The benefit-risk relationship of mRNA-1273 is not affected by this report.   This case was linked to MOD-2021-404099 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 16-Dec-2021: Follow up received on 16-Dec-2021, which contains patient demographic details (race, height and weight), Lab data and a new event Pain in extremity was added.; Sender's Comments: This case concerns a 50-year-old, female patient with relevant medical history of allergy who experienced the unexpected event of monoplegia (IME). The event occurred the same day after the second dose of mRNA-1273. The rechallenge was not applicable since the event happened after the second dose. The benefit-risk relationship of mRNA-1273 is not affected by this report.