developed a little red spots on the back of their leg, close to their knees/both of her legs are red and a little bit swollen close to her knee on the back of her calf; a little bit swollen, when she touch it it's hard and it's very red; When she touches her leg she feels the pain by the touch; swelling in her arm pit; fever; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient. A female consumer (patient) reported for herself.   A 32 year-old female patient received bnt162b2 (BNT162B2), administration date 30Sep2021 (Batch/Lot number: unknown) at the age of 32 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "Allergies: regular allergies" (ongoing). There were no concomitant medications. Vaccination history included: Bnt162b2 (Dose 1, single), for COVID-19 immunization, reaction(s): "She never had this with her 1st or her 2nd dose"; Bnt162b2 (Dose 2, single), for COVID-19 immunization, reaction(s): "She never had this with her 1st or her 2nd dose".  The following information was reported: RASH MACULAR (non-serious) with onset 01Oct2021, outcome "not recovered", described as "developed a little red spots on the back of their leg, close to their knees/both of her legs are red and a little bit swollen close to her knee on the back of her calf"; PERIPHERAL SWELLING (non-serious) with onset 01Oct2021, outcome "not recovered", described as "a little bit swollen, when she touch it it's hard and it's very red"; PAIN IN EXTREMITY (non-serious) with onset 01Oct2021, outcome "unknown", described as "When she touches her leg she feels the pain by the touch"; SWELLING (non-serious) with onset 01Oct2021, outcome "recovered" (03Oct2021), described as "swelling in her arm pit"; PYREXIA (non-serious) with onset 01Oct2021, outcome "recovered" (03Oct2021), described as "fever".   Additional information: Consumer reporting side effects from the Pfizer BioNTech Covid19 Booster dose. Per caller, she and her boyfriend had the booster dose, she had her booster dose on 30Sept2021, while her boyfriend had the booster dose on 01Oct2021. They both developed a little red spots on the back of their leg, close to their knees. She developed the red spots last night, while her boyfriend developed the day after the shot. She described it as a little bit swollen, when she touch it and it was hard and it was very red. She also added that the red spot is exactly behind her knee. The patient's both of her legs are red and a little bit swollen close to her knee on the back of her calf was worsened. The reporter seriousness for the events was unspecified. Reason for no lot number: of COVID vaccine: Other: Caller does not have her COVID vaccine record card to provide this information. Caller states that she took her booster dose of the COVID vaccine on Thursday night and she had the regular expected side effects up until yesterday. But today, right now, both of her legs are red and a little bit swollen close to her knee on the back of her calf. It is the weirdest pain that she has ever felt. She never had this with her 1st or her 2nd dose. She was reading about these kinds of things online and she doesn't know if this has happened before. She also had swelling in her arm pit, fever and all the other expected side effects but this on her legs just started now and it is on both of her legs. Event Details: She had her booster dose on 30Sep2021 and the side effects started on Friday, 01Oct2021, 15 hours after the booster. Her expected side effects went away yesterday, 03Oct2021. Inquired when the red and swelling began on her legs and she states that yesterday she felt a light pain at night and she had went to sleep. She thought that it was because she was tired but now the pain hasn't decreased at all. When she touches her leg she feels the pain by the touch. When she tried to check her leg she saw the red. Her boyfriend took the vaccine on Friday and he started with this yesterday, the same thing as her, but his is just on one leg. Inquired for outcome of her legs and she says yesterday it was there only slightly, now it is worse. Inquired for NDC, lot number and expiry date and she says that she is unable to provide that because her COVID vaccine card is at home and her internet is not working so she doesn't have access to pulling up the information.   The follow-up is being submitted to notify that the lot/batch number is not available despite the follow-up attempts made. Follow-up attempts completed. No further information is expected.