she has watery blister there filled with yellow fluid in them/got blisters right there at the injection site; arms were a lot more sore; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 71 year-old female patient received bnt162b2 (BNT162B2), administered in arm (Lot number: EN6205) as dose 2 , single for covid-19 immunisation. Relevant medical history included: "cardiac ablation" (unspecified if ongoing), notes: in January last year before COVID hit.; "leukemia" (unspecified if ongoing). There were no concomitant medications. Vaccination history included: Bnt162b2 (DOSE =1), for covid-19 immunization, reaction(s): "Headache"; Bnt162b2 (Dose 1,EL9264), for covid-19 immunization, reaction(s): "pain in arm". The following information was reported: VACCINATION SITE VESICLES (non-serious), outcome "unknown", described as "she has watery blister there filled with yellow fluid in them/got blisters right there at the injection site"; PAIN IN EXTREMITY (non-serious), outcome "unknown", described as "arms were a lot more sore".  Additional information: They did pretty good with side effects for the 1st injection, their arms were sore and she had kind of a slight dull headache part of the time but it was okay when you consider not taking the vaccine what could happen that was okay. But their arms were much more sore this time. She is high risk, she had cardiac ablation January last year before COVID hit. She was lucky to get in and out of the hospital and get her cardiac ablation before all this happened. She was on 4-5 different heart meds since the ablation, she did well and they also discovered she has leukemia while she was in the hospital for Afib she guesses it was lucky that happened. It is not a serious form of leukemia it is the one they say you will die of something else before you die of this. She was hopeful that the blisters would reabsorb but one of them did burst yesterday so at least part of that did not reabsorb, it is kind of a yellowish fluid and she has taken pictures.  She really would like to know that she didn't mess up the second dose and pull the serum to the surface of the skin and lose the efficacy. She adds the Hot Hands package says average temperature of the packet is 97 degrees Fahrenheit, it says you are not supposed to squeeze the packet and break the granules to activate the packet, it could make it higher than it is supposed to be and they were crunching on the packets. She did not read the instructions before use. The patient stated after vaccination site was hot and watery blister and filled with yellow fluid. She says their arms were a lot more sore this time and her husband had these packets you pop open they are like hand warmers, they are little disks with adhesive on it and she stuck it to the injection site but it got too hot so consequently she got blisters right there at the injection site and she is concerned that the heat and the blisters may have pulled the serum out of her body. She should have taken hers off when he was complaining about his being too hot but she did not and now she has blisters on her arm. She found the package of the hand warmers. It is called Hot Hands and they are actually toe warmers that you stick to the bottom of your socks in your shoes. If she had bothered to read the fine print it probably says do not put directly against the skin, it is not their fault. Patient received the second dose of the Pfizer covid vaccine Monday and they put the hot compress on the vaccination site. She stated it was too hot and now she has watery blister there filled with yellow fluid in them. Patient wanted to know did she compromised her immunization due to this. her husband did not get the blisters. Patient stated they pulled a really stupid, they were going along fine, they got the second injection and their arms were a lot more sore this time and she was putting warm moist compresses on her arm but her husband got the bright idea, he had these packets you pop open they are like hand warmers, they are little disks with adhesive on it and she stuck it to the injection site but it got too hot so consequently she got blisters right there at the injection site and she is concerned that the heat and the blisters may have pulled the serum out of her body. She feels like such an idiot. He had gotten these hand warmers out and he had his on his arm and he started complaining that his felt too hot and he took his off. She should have taken hers off when he was complaining about his being too hot but she did not and now she has blisters on her arm. Patient said she must not be awake. This second dose was given on Monday, this week, she is not looking at a calendar so she is not sure about the date. She says the soreness began in the arm immediately, the same day. She actually thinks they got the shot on Wednesday, no she doesn't know what is wrong with her brain, she is going to go ask her husband. She clarifies it was Monday that they both got the second dose. It was Tuesday evening when she used the hand warmer product and got blisters. She is sure they have a box around there somewhere of the hand warmers, they are about the size of your palm and you squeeze it and it heats up, there is adhesive on one side and she stuck it over her injection site, she had been using a warm wash cloth for a compresses but it just cooled off too quick. They told them to use warm compresses on your arm if they were sore but it cooled off too quick so she thought the hand warmer would be good but with it being such a small little pack, she couldn't tell it was that hot in such a small area. She didn't take a picture when she first saw the blisters, they were considerable but she did take pictures of it later, about 24 hours or probably 12 hours later but some of it did bust.  No follow-up attempts are possible. No further information is expected.