Intense lower leg pain and weakness in the legs; the pain became really intense and she felt like she really could not walk; Intense lower leg pain and weakness in the legs; This is a spontaneous report from a Pfizer sponsored program via a contactable consumer. A 28-year-old female patient received second dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, formulation solution for injection, Batch/Lot Number: ER8733), via an unspecified route of administration, administered in Arm Left on 20May2021 15:45 as 2nd dose, single for COVID-19 immunization. The patient medical history was reported as none. The patient concomitant medications were not reported. The patient did not receive any other vaccines within four weeks, prior to vaccination. Patient's family medical history related to AE was none. The patient previously took first dose of BNT162B2 (Lot: EW0162) on 29Apr2021 in upper left arm at about 15:30. Patient clarified that she did not receive her first dose of Pfizer Covid Vaccine last Thursday, 20May2021 she received her second dose of Pfizer Covid Vaccine last Thursday 20May2021. She clarified that she had onset of intense lower leg pain and weakness in both legs after having received the second dose of Pfizer Covid Vaccine. She verified that she called to ask if these events are common or known side effects of the Pfizer Covid Vaccine. Intense pain in lower legs initial onset was on 21May2021, probably around 21:00, but was minimal pain at that time, and it improved by around Sunday, 23May2021 or the 3rd or 4th day after onset. Yesterday, 25May2021, around 10:00-11:00 the pain became really intense and she felt like she really could not walk; then she clarified that she is able to walk; but she is experiencing severe intense pain that is very abnormal for her. It is not normal pain, not something normal. She had not had any unusual physical activities everything is normal but both legs are hurting in the lower part of the legs. If she just keeps walking the pain is intense; if she just sleeps all the time it's fine, the pain improves. The Intense pain in lower legs is getting better. Weakness in both legs initial onset was on 25May2021 probably around 10:00-11:00 when the intense pain in lower legs worsened. She feels a lot of weakness in both legs, something like how if you experience a very serious illness and feel so weak; it is like that. Like she has no energy in her legs. When she sleeps for a long time the weakness does not improve like the pain does, and the weakness feeling gets very unusual. She does not think it worsens when she sleeps for a long time, but it is pretty much the same as when she does not sleep for a long time. She reported this event worsened this morning, felt more weakness in both legs this morning. On 21May2021 21:00, patient experienced intense lower leg pain and weakness in the legs, but was minimal pain at that time, and it improved by around Sunday, 23May2021 or the 3rd or 4th day after onset. If patient just keeps walking the pain is intense; if patient just sleeps all the time it's fine, the pain improves. The Intense pain in lower legs is getting better. On 25May2021 probably around 10:00-11:00 when the intense pain in lower legs worsened she feels a lot of weakness in both legs. When patient sleeps for a long time the weakness does not improve like the pain does, and the weakness feeling gets very unusual. patient reported this event worsened this morning, felt more weakness in both legs this morning. The events were considered as non-serious. The events resulted in urgent care visit. The outcome of the event intense leg pain was recovering and outcome of event weakness of both legs was not recovered, outcome of the event she felt like she really could not walk was recovered on an unknown date in 2021.  Information on lot/batch number was available. Additional information has been requested.