When she saw her sister on 30Apr2021 to celebrate her sister's birthday, her sister had 2 black-eyes from the fall; my sister couldn't breathe; Her sister took her dog for a walk and fell; had "jelly legs," and couldn't walk very well; had "jelly legs," and couldn't walk very well; This is a spontaneous report from a contactable nurse. This nurse reported for a 47-year-old female patient (sister) received first dose of BNT162B2 (PFIZER-BIONTEC COVID-19 mRNA VACCINE, Solution for injection, lot number: ER8737 and expiry date was not reported), via an unspecified route of administration, in Arm Left, on 10Apr2021 at 16:00 PM (age at vaccination: 46 years), as a single dose for COVID-19 immunization. The patient's medical history included had bipolar disorder for at least 15 years, if not longer. The patient had bouts of depression before finally being diagnosed with bipolar disorder. The patient took a cocktail of medications that work for her and keep her very steady. The patient sees a doctor every 3 months for her bipolar disorder. No further details provided. Concomitant medications were not reported. Caller was a registered nurse calling on behalf of her sister. Caller was inquiring about additional information regarding Guillain-Barre syndrome in people who have received the Pfizer Covid-19 vaccine. Caller reports her sister received both doses of the Pfizer Covid-19 vaccine with her second dose being 01May2021. Caller reported her sister has since experience trouble walking and they were awaiting results of a possible Guillain-Barre diagnosis. Caller stated she was having a hard time getting someone to see her sister. Caller asked "what were other people doing in this situation and should I take her back to the ER, could be a medical emergency". Caller reported that her sister has a neurology appointment 13Aug2021 and she has called them multiple times to be seen sooner, but they won't. Caller reported one doctor sent her for a muscle biopsy saying she had myasthenia gravis, but another doctor said it could be Guillain-Barre syndrome from the Covid shot. Caller stated, "I have to go on vacation with my daughter and my husband in the meantime and I'm scared to leave her alone with just my mom". Caller asked "what should we do and was there a team of doctors you could put us in touch with or someone you could call. Caller stated, "my mom didn't go to church yesterday because my sister couldn't breathe". Caller tearfully stated, "I don't know if she'll come back from this". Caller reported on her sister who had both doses of the COVID-19 Vaccine. After her sister went for the first COVID-19 Vaccine dose, her sister had "jelly legs," and couldn't walk very well on an unspecified date in Apr2021. Her sister took her dog for a walk and fell. She remembered her sister fell on Sunday, 25Apr2021, while her sister was walking her dog. Her sister fell on her face, and knees. When she saw her sister on 30Apr2021 to celebrate her sister's birthday, her sister had 2 black-eyes from the fall. Caller reported her sister's neighbours helped her up and grabbed her sister's dog. Her sister said she went in her house and cleaned herself up. Her sister didn't think she broke anything. No further details provided. The patient did not received any treatment for the events. Outcome of the events was unknown.; Sender's Comments: Based on the information in the case report, a possible causal relationship between fall,gait inability,limb discomfort and suspect product BNT162B2 cannot be excluded.  The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.