She didn't feel well last night; Weakness in left thigh and leg/leg was so weak she could not get up; Fell down 3 times; This is a spontaneous report from a contactable consumer (patient) and healthcare professional. A 65-year-old female patient received first dose of bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE; lot EL1283), via an unspecified route of administration on 25Jan2021 11:30 at single dose (arm left) for COVID-19 immunization. Medical history included costochondritis, vertigo, autoimmune disease, uses a walker, inflammation of the cartilage between the rib and sternum and pulled muscle. Concomitant medications included methylprednisolone (MEDROL) (also reported as steroid pak) from Jan2021 to Jan2021 for pulled muscle and ketorolac tromethamine (TORADOL) from Jan2021, both for inflammation of the cartilage between the rib and sternum. The patient previously took iodine and experienced allergies. It was reported that the patient just got the first Pfizer BioNTech Covid-19 vaccine yesterday, 25Jan2021, 11:30 am. Last night, at 19:00, she had weakness on the left side of the body, especially in the thigh, and she fell down 3 times last night. Her leg was so weak she could not get up. She just got off the phone with the doctors office and was told to report this. The patient did not received therapy for the events weakness in left thigh and leg/leg was so weak she could not get up and Fell down 3 times. On 26Jan2021, the patient experienced didn't feel well last night. She was also on a Medrol pack about a week ago and just finished her last dose last night when she took the vaccine. The nurse practitioner at the doctor's office was wondering if it could have been an interaction between the Medrol pack and the vaccine. She got an email saying she could get the vaccine, but didn't think to call the doctor office to ask about the Medrol pack (steroid pack) or if it could cause any interactions. So the office told her to call. Later mentions along with the Medrol pack, she got an injection in the office of Toradol and this was before getting the vaccine.  She stated that she did have her on a steroid pack for a pulled muscle so that may have exacerbated the issue. The weakness and things have improved so she was still a little nervous and uses a walker and just making sure to take it easy today. The patient had no other vaccines in 4 weeks and other medications in two weeks included steroid Pak. Patient had no problems with vaccines in the past. The patient had no Covid prior vaccination and was not Covid tested post vaccination. The patient had no events following prior vaccinations. Patient stated that they had been lucky and they have been tested before and has not had it yet, so that was why they wanted to get the vaccine done. She just rested and her husband helped her to bed since she didn't feel well last night. She did not have any trouble breathing. Patient underwent a Chest x-ray in Jan2021 and nothing showed up on it, but just some old calcifications from many years ago. That was done sometime last week and she also had like 3 MRI's on an unspecified date. Patient was wondering if she should she get the second dose. Her next appointment was on 16Feb2021. She was pretty banged up and does not want to have to go through that again. Outcome of events was recovering.