hair is getting thinner and thinner; 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. Other Case identifier(s): US-PFIZER INC-202101573657 (PFIZER).  A 72 year-old male patient received bnt162b2 (BNT162B2), intramuscular, administered in arm left, administration date 01Oct2021 11:15 (Lot number: 30135BA, Expiration Date: Nov2021) at the age of 71 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "male pattern baldness" (ongoing). There were no concomitant medications. Vaccination history included: Bnt162b2 (First dose, Batch/Lot number: EN6201, Expiration date: Jun2021, Time (24hr): 10:40, Anatomical Site of injection: Left arm, Route of administration: Intramuscular), administration date: 12Feb2021, for Covid-19 immunization; Bnt162b2 (Second dose, Batch/Lot number: EN6203, Expiration date: Jun2021, Time (24hr): 2:30, Anatomical Site of injection: Left Arm, Route of administration: Intramuscular), administration date: 08Mar2021, for Covid-19 immunization; Fluzone hd (Manufacture: Sanofi, Batch/Lot#: UJ702AB, Route: IM, Anatomical Site of Injection: R-Deltoid), administration date: 16Sep2021, for Influenza immunisation. The following information was reported: ALOPECIA (non-serious) with onset 2021, outcome "unknown", described as "hair is getting thinner and thinner". The event "hair is getting thinner and thinner" was evaluated at the physician office visit.  Additional information: Patient was a little concerned and he asked his doctors office. On 01Oct2021 he received his third shot of the Pfizer covid vaccine. In the past couple of weeks he noticed that his hair is getting thinner and thinner at an accelerated rate. He already had male pattern baldness prior to this. Patient had been have been losing his hair for a long time, but it just seems like it was thinning faster. He had an appointment coming up with his primary doctor. He went to the office to ask but the doctor was not there and someone at the office told him it could be male pattern baldness. Stated that he hardly has any hair anyhow but he noticed it is getting thinner and couple of weeks ago he needed a little trim but now it looks like he got a trim. Patient had bald patter hair loss, but he did have hair on the side which needed trimming, but now it thinning on its own. The patient wanted to know if it is a common side effect. Just wanted to make sure if it was the vaccine, Patient heard the vaccine may cause your hormones to accelerate and some people have had hair growth. Patient was going to see his PCP next week and just wanted to make sure he have some information to tell him. No other relevant diagnostic and confirmatory test results for event(s), for example, from blood tests, cerebrospinal fluid culture, pleural fluid culture, urine culture, diagnostic imaging, (e.g., chest X-ray, MRI) performed. No COVID-19 testing had been conducted. Specific Relevant Test for Thromboembolic Events with Thrombocytopenia was none. Noticed hair getting thinner or both sides of head after making report and being told, not a side effect went and had reminder of hair out. Cause- natural balding process.  No follow-up attempts are possible. No further information is expected.