she starting losing some weight during the time of the vaccines; thyroid function having a problem in regards to the mrna vaccines; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non-HCP) from medical information team, Program ID: (159558). The reporter is the patient.  A 74-year-old female patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), in Sep2022 as dose 4 (booster), single (Batch/Lot number: unknown) at the age of 74 years for covid-19 immunisation. The patient's relevant medical history included: "Thyroid" (unspecified if ongoing). The patient's concomitant medications were not reported. Vaccination history included: Bnt162b2 (DOSE 1, SINGLE), for COVID-19 immunization; Bnt162b2 (DOSE 2, SINGLE), for COVID-19 immunization; Bnt162b2 (DOSE 3 (BOOSTER), SINGLE), for COVID-19 immunization. The following information was reported: WEIGHT DECREASED (non-serious), outcome "unknown", described as "she started losing some weight during the time of the vaccines"; THYROID DISORDER (non-serious), outcome "unknown", described as "thyroid function having a problem in regard to the mrna vaccines". Relevant laboratory tests and procedures are available in the appropriate section.  Additional information: The patient had received four of the Pfizer BioNTech Covid-19 mRNA vaccines for adults, the 4th one was the bivalent omicron vaccine for adults. She stated it seemed she started losing some weight during the time of the vaccines. Her PCP does lab work every 6 months on her thyroid. The one in June showed her thyroid was a little off and the one in November, the PCP said, she needed to start taking 6 pills of her thyroid medication a week instead of 7. She lost some weight, and her blood pressure was off and a number of things. She was reading online where some of the vaccines could affect the thyroid medications. In 20 years of taking thyroid medication, she has never had a problem with it, the level of medicine has never been thrown off and the only thing new would be this vaccine. She had minor reactions with the first 3 Covid vaccines and the 4th was stronger. She stated the 4th one, her last one, was in September. She just knows over the last year and a half she had lost some weight and her blood pressure was up out of nowhere, just things going on that didn't make sense. She saw an allergist in October, and they noticed she lost some weight, but she had lost weight months before that. She had gone down a whole size in her clothes. She stated this was good for her but it was out of nowhere and she had not been dieting. She does not remember the specific numbers for her labs to report them. She is going to see a new doctor because she was not sure her PCP would be the one to help do further testing and she won't see him until June so she was going to find a new document because she does not have an endocrinologist. The caller wanted to know about whether there were any studies on thyroid function changing after the vaccines. The patient had four of the mRna vaccines for Covid and she wanted to know about thyroid function having a problem in regards to the mrna vaccines.  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.