This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP) for a Pfizer sponsored program (005570). The reporter is the patient. A 81 year-old female patient received bnt162b2 (BNT162B2), administered in arm left, administration date 02Dec2021 10:00 (Lot number: FH8027) at the age of 81 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "borderline diabetes" (unspecified if ongoing), notes: Patient's Medical History: borderline diabetes. Concomitant medication(s) included: METFORMIN taken for glucose tolerance impaired (ongoing). Vaccination history included: Bnt162b2 (First Dose, Lot: EL9265, Expiration: unknown, Anatomical location: left arm, She did not have any problem with the first two shots of the covid vaccine.), administration date: 17Feb2021, when the patient was 80 years old, for Covid-19 Immunization, reaction(s): "She did not have any problem with the first two shots of the covid vaccine."; Bnt162b2 (Second dose, Lot: EL9269, Expiration: unknown, Anatomical location: left arm, She did not have any problem with the first two shots of the covid vaccine.), administration date: 10Mar2021, when the patient was 80 years old, for Covid-19 Immunization, reaction(s): "She did not have any problem with the first two shots of the covid vaccine."; Flu shot (She had no problems with flu shot.), for Immunization, reaction(s): "She had no problems with flu shot". The following information was reported: IMMUNISATION (non-serious) with onset 02Dec2021 10:00, outcome "unknown", described as "Covid booster shot"; CHILLS (non-serious) with onset 02Dec2021 09:00, outcome "recovered" (03Dec2021), described as "Chills/getting cold and got colder and colder/shivering"; NASOPHARYNGITIS (non-serious) with onset 02Dec2021 09:00, outcome "recovered" (03Dec2021), HEAD DISCOMFORT (non-serious) with onset Dec2021, outcome "recovered" (Dec2021) and all described as "pressure on left side of her head"; NIGHT SWEATS (non-serious) with onset Dec2021, outcome "recovered" (Dec2021), described as "woke up soaking wet"; DIZZINESS (non-serious) with onset Dec2021, outcome "recovered" (Dec2021), described as "Light-headed"; CHILLS (non-serious) with onset 02Dec2021, outcome "recovered" (03Dec2021), described as "so cold her teeth was chattering"; FATIGUE (non-serious) with onset 03Dec2021, outcome "not recovered", described as "extremely tired"; INSOMNIA (non-serious) with onset Dec2021, outcome "not recovered", described as "Took two naps".  No follow-up attempts are possible. No further information is expected.  Additional information: The patient had no other products, no investigation assessment and no family medical history relevant to AE. The patient was calling about the covid booster shot. She had a problem with it. She received the booster on Thursday. Thursday night she not only had, but she was also. She was in bed for a couple of hours and her teeth were still chattering. On day two she and was and she does not know if it is classified as a headache, but she had more like. Her naps were two hours in the morning and three hours in the afternoon. She went to bed at 21:00. At 02:00 she, even her hair was wet, like she just got out the shower. On Day three, she did the same thing with the naps and she felt the same way and. Come night at 04:00, she woke up and she was wet again, her night clothes and hair was wet. Not quite as wet as the day before on day 3. Last night was night 4, and she did not have any problem last night, however, she was still very tired. She just woke up from a three hour nap and she just feels that someone should not what happened to her. She did not have problems with the booster. She was still mowing her own lawn and is still active. Height: Used to be 5'3" and she is close to that unless she shrunk a little. Exactly 21:00 on Thursday was when she started getting cold and got colder and colder for 20 minutes. Started with her hands being cold at night and thought to put them in the pocket of her bath robe and did not get warmer and she was getting chills and was shivering. Treatment declines any. The only thing that remains today was being tired and taking three hour naps and she normally does not nap at all. Metformin dispensed in a pharmacy bottle: States it was a big tablet. She sees a S/N and GTIN. Manufacturer : Granules Pharmaceuticals Incorporated, NDC: thinks the fine print states NDC: 68645-584-59. Product strength and count size dispensed: 100mg tablet, 90 days. She had three bottles like this. She only had this bottle that she has opened. She had other bottles that has not been opened yet. She was not on insulin. She called first and was frustrated. Patient did not visit to emergency room and physician office. Patient did not take any prior vaccine within 4 weeks. Patient did not experience AE following prior vaccination. No relevant tests done. There was product complaint. Description of complaint: Metformin dispensed in a pharmacy bottle: States it is a big tablet. She sees a S/N and GTIN.  Follow-up (08Dec2021): Follow-up attempts are completed. No further information is expected.