hurts to walk; it is hard for her to get up to walk, so she has to use a walker; lower back pain that moves to the right of her spine; hurts so bad to sit down; slight headache; her eyes have gotten weaker; when she sits on her bottom, there is a throbbing pain right around the top of her butt crack; this new pain started right after she got the vaccine; This is a spontaneous report from a contactable consumer. A 75-years-old female patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, Solution for injection, Lot number : ER8731 and Expiry date: Unknown), dose 1 via an unspecified route of administration, administered in Arm Right on 24May2021 at 14:30 as single dose for covid-19 immunization. Medical history included ongoing myasthenia gravis from Dec2020, ongoing anemia, ongoing migraine, right partial knee replacement from an unknown date at the end of 2016 or 2017 (her right leg did not bother her), ongoing back pain, stroke in the Spring of 2017 or 2018 (stroke only lasted 10 minutes and that she had numbness in her left arm and leg but has had no lasting effects), multiple surgeries on an unknown date, had a fractured tailbone on an unknown date, had multiple epidurals on an unknown date from 2019 to an unknown date (her last one was in the summer of 2019 for back pain), depression from an unknown date and unknown if ongoing. Concomitant medication included valaciclovir hydrochloride (VALTREX, Tablet) taken for shingles, start and stop date were not reported. The patient stated that her doctor wondered if she had shingles, so he told her to call him if she developed more spots. The patient stated that there was a place that came up on her lower left buttock, so she called him and he called in a prescription for Valtrex to treat the shingles. The patient did not remember the exact start date but states that it was after her appointment with the dermatologist on 19May2021. The patient stated that the dosage was supposed to be 2 pills a day for 3 days, but because they were 500mg pills, her doctor changed the dose due to her myasthenia gravis. The patient stated that she was concerned because she was on Plavix and she was on three pills for her immune system, so she thought they would know that already because she has myasthenia gravis. The patient previously took cortisone acetate for lower back pain, tremadol for back pain. The patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. The patient received other medications within 2 weeks of vaccination. The patient was not diagnosed with Covid 19 and had not been tested for COVID-19 since the vaccination. No additional vaccines administered on same date of the Pfizer suspect. No adverse events required a visit to: Emergency Room, Physician Office. She stated that she received the COVID vaccine because of her condition, myasthenia gravis, her doctor wanted her to have it because she would be at risk due to the things that this disease causes and that if she got the COVID, if it affected her breathing or something like that, it would be critical. The patient stated that she had been homebound since she got out of the hospital in January and her husband got his shot, so they wanted her to have it as soon as she could so she would not get the COVID, with all the conditions that she had. The patient stated that when she saw her dermatologist, there was a place on her left buttock that looked like dried up blisters. She said that her myasthenia gravis was an autoimmune disease and she was taking three different medications. The patient stated that she did not know exactly when this started but that she had effects from it in Dec2020. She was checked for it several years ago because her mom had it and they said that she did not have it, but before COVID started she had blood work done and her doctor said that she did have it and then after that the neurologist did a test and they said that she did not have it, and she had sinus infection and they gave her medication and prednisone, and after that it hit her. The patient stated that they were trying to wait until they weaned her down on prednisone, but they decided to let her get the first shot of COVID, three weeks ago this Monday. She stated that she was scheduled for her second vaccine 14Jun2021. She stated that she did not know where to start, she was unsure it these issues were from her myasthenia gravis or if it was related to the COVID shot. The patient stated that the morning of her vaccine, she had an appointment with her neurologist. The caller stated that at the time her eyes were feeling better, and her doctor thought she looked better, and overall she felt better. She clarified that she was still having some issues and was still using her walker, but that afternoon she went to get the shot, and she did not even realize it, because she could not feel it and her arm never got sore. The caller stated that her weight fluctuated depending on her fluid levels. The patient stated that last week she had two sessions of IVIG treatment for myasthenia gravis. She stated that this might be from the healing of her tailbone, which had been going on for 6 weeks. The patient stated that she has had lower back pain that moved. Sometimes it was to the right of her spine, and then on her bottom, it hurted so bad to sit down and it hurted to walk on an unspecified date. She also stated that she has had a slight headache, the past two or three nights on an unspecified date. The patient stated that the headache started at the very bottom right part of her head. The patient said that she never felt weak on Tuesday after she had that treatment, that it was like a normal day, but then it seemed like her issue of not being able to walk, that was more painful. The patient also stated that her eyes had gotten weaker on an unspecified date. The patient stated fractured prior to fractured her tailbone, she started having pain in her left buttock. She thought that started prior to 30Apr2021 because she went to her doctor for a regular appointment and she told him that she was having issues and she thought it was the sciatic nerve because she has had that in the past. The patient stated that they lifted her leg and everything checked out fine, that nothing major was going on. The caller stated that she told him she hurt something in her lower back. The patient stated that she went back to the doctor on 29Apr2021 and she was diagnosed with chronic left sided low back pain and they sent her to have a MRI on 30Apr2021. The caller stated that when they did the MRI they found out that she had a fractured tailbone but she has not fallen in the last year. The patient stated that the pain she was having in her buttock from the fractured tailbone has stopped. She states that when she was having that pain, it was sharp, excruciating pain and she could not hardly put weight on the left side of her foot on an unspecified date. The doctor told her to keep her feet up and move around a little at a time. The patient stated that she was not bedridden, and that pain lasted probably 2-3 weeks, but has gotten better. The patient stated that now she is having pain in her low back to the right of her spine and when she sits on her bottom, there is a throbbing pain right around the top of her butt crack on an unspecified date. The patient stated that it throbbed and it was hard for her to get up to walk, so she had to use a walker and it was a different pain, it was not the same pain as before when she broke her tailbone. The patient stated that this new pain started right after she got the vaccine, but then it seemed like it got worse after she had the IVIG. The patient underwent lab tests and procedures which included blood test: normal on 30Apr2021, magnetic resonance imaging: she had a fractured tailbone on 30Apr2021. When asked about investigations after she received the vaccine, the caller stated that she has not had any tests performed because she did not know if it was from her myasthenia gravis or not. No other relevant tests were reported. Treatment details were not provided. The outcome of events was unknown.  Information on Lot/Batch number was available. Additional information has been requested.