weight gain, 40 pounds; fatty liver; This is a spontaneous report from a via contactable consumer (patient, self-reported).  A 63-year-old female received second dose of BNT162B2 (PFIZER-BIONTEC COVID-19 mRNA VACCINE, Solution for injection, lot number: EN6205 and expiry date was not reported), via an unspecified route of administration, in Arm Left, on 09Mar2021 at 13:00, as a single dose for COVID-19 immunization. The patient's medical history included ongoing hypothyroidism (has been on levothyroxine), end stage COPD, autoimmune deficiency (common variable immuno deficiency and she got Gammagard for this) and celiac disease. Historical vaccine included first dose of BNT162B2 (PFIZER-BIONTEC COVID-19 mRNA VACCINE, Solution for injection, lot number: EM9810 and expiry date was not reported), via an unspecified route of administration, in Arm Left, on 18Feb2021 at 13:00, as a single dose for COVID-19 immunization and no reaction on previous exposure to vaccine. Concomitant medication included levothyroxine sodium (LEVOTHYROXINE) for hypothyroidism (taking for several years). The patient took Pfizer Covid-19 vaccine because to prevent Covid. The patient did not receive any vaccine within 4 weeks prior vaccinations. There was no AE following prior vaccinations. There was no family medical history relevant to AE. There was a product complaint. The patent reported that on an unspecified date in 2021, she was experiencing weight gain, 40 pounds since receiving second dose of vaccine (doses were given in Feb and Mar2021) and other than maybe 3-4 weeks after she was administered her second dose. She was wondering if this could be from the vaccine. The response included that a review of the prescribing information for the Pfizer COVID-19 Vaccine did not find information regarding weight gain. As the prescribing information did not include all adverse reactions that have been reported or that may occur, please consult with your doctor/healthcare provider about what you had experienced/were experiencing. She stated that she had hypothyroidism and has been on levothyroxine and was looking to see if the vaccine could effect her thyroid condition because she was noted that her blood test did show an increase in her numbers since Jan2021 and she received the vaccine in Feb2021 and Mar2021. She did recently do back to her HCP to have repeat blood work (unknown result), and sonogram, which showed a fatty liver on an unspecified date in 2021, however he did not include thyroid testing in this last blood work. She was sitting on her butt, calling it Covid fat which she called bullshit. She's been skinny up until after the second dose of Pfizer Covid-19 Vaccine. She went to the primary physician's office because she's concerned about gaining weight. He said to eat a low-fat diet; but she did eat a low fat diet. She eats salad for supper, eats no gluten, eats gluten free bagel for lunch, a banana for breakfast; she even used the salad dressing that was fat free and sugar free; there was no fat in her diet. Her weight normally was between 105lbs and 100lbs. She was usually skinny, autoimmune deficiency skinny, she did not gain a lot of weight. She has been progressively gaining weight since onset, she was 103lbs and was now 140lbs and was about to pop like a balloon. She explained regarding testing/investigations that she asked her doctor to do a blood draw to check levels for thyroid; they were doing a whole bunch of them to try to figure out what's going on. When she got the blood draw results there was no thyroid check. She asked the nurse to go back a few, to like 2000 to check the thyroid parts of the blood draws and since Mar of unknown year, between Mar and Jan of unknown years before she ever got the Pfizer Covid-19 Vaccine her thyroid numbers went up. The doctor was usually pretty good at this stuff; but to leave out something she specifically requested in a blood draw, the thyroid levels, because she was thinking that's what was going on; because she didn't balloon like this. The adverse events did not require a visit to emergency room. They suggested she go one time, but she wasn't going to go for that, all they would do was jab and her and not tell her anything. The patient visited at physician office. Outcome of the events was not recovered.  Information on Lot/Batch number was available. Additional information has been requested.