feels tired; heart rate became very fast, it went into like the 150's; feeling jittery; Lightheadedness; weakness of lower extremities; Nauseated; felt really cold; probably had a fever; really thirsty; very hot; she wasn't feeling well; This is spontaneous report from a contactable nurse (patient). A 36-year-old female patient received the first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, lot number: EJ1686), intramuscular (deltoid left) on 14Jan2021 18:25 at 0.3 mL, single for Covid-19 immunization. The patient's medical history was not reported. There were no concomitant medications. The patient previously took Bactrim and experienced allergy. The patient reported she did develop some side effects, but the hospital she received the vaccine at didn't know if it was an allergic reaction or what. She reported that a minute or two minutes after receiving the COVID-19 vaccine (14Jan2021), her heart rate became very fast, it went into like the 150's. She started feeling jittery, lightheaded, and she had some weakness of her lower extremities. She also felt nauseated. She didn't have any shortness of breath; she thinks she was okay there. She clarified that she had her mask on and they told her to remove her mask and to breathe, breathe, breathe. She had a pulse oximeter on, and her levels were always at 98, 96. She was told to sit still, and she was given water. Her heart rate went down to 76. She was fine and then after 5 minutes, she had the same reaction again. Her heart rate this time was in the 120's. She was lightheaded, cold, jittery. She did the same thing again and waited another 5- 10 minute. She felt better but was still nauseated, lightheaded, and really, really cold. She was kept there for 45 minutes. After that, she still did not feel 100%. Currently, she still does not feel 100% well. She was okay, she thinks she was okay. She explains they wanted to send her to the ER (emergency room) but she declined. Her heart rate had improved, she wasn't feeling like she was going to pass out. She wasn't experiencing shortness of breath, she wasn't throwing up, she didn't have a rash, her throat wasn't closing up, so she went back to work. She further stated that she came back home. Her heart rate was a little faster, but it wasn't as high as it had been. She still felt a little bit of weakness. At night (14Jan2021), she probably had a fever, she doesn't know. She was really thirsty and very hot. Because she was not feeling well, she didn't get up and drink anything. This morning (15Jan2021), she feels a little better. If she is doing her normal activities, she does get tired. She feels like she is running and is like "okay I feel tired". She has a little bit of weakness in her lower extremities. She was given information for reporting side effects, but because she wasn't feeling well, she didn't do any of it. She checked her heart rate today (15Jan2021) and it's at 76. She added that when she moves a lot, she feels tired and she doesn't know why. She's normally a very active person. She is no longer jittery, but still feels lightheaded. She has a little bit of nausea. She felt hungry so she made a shake and it's not like she is going to throw up, but she is still feeling yucky. She still has a little weakness of her lower extremities. They feel light, she doesn't know how to explain it. She is just a little bit concerned because this is a new vaccine. The outcome of event heart rate increased was recovering; outcome of event feeling jittery was recovered on an unspecified date; while the outcome of other events was unknown. The patient confirmed he doesn't believe it to be life threatening. She doesn't know if this is a severe allergic reaction. She was reading on the side effects the COVID-19 vaccine can cause. Per reporter all events were related to suspect product.; Sender's Comments: Based on the compatible time association, the contribution of suspect BNT162b2 to the event heart rate increased 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.