low iron; hemoglobin dropped; The initial safety information received was reporting only non-serious adverse drug reaction(s), Upon receipt of follow-up information on [18Oct2022], this case now contains serious adverse reaction(s). Information processed together.  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 66-year-old male patient received BNT162b2 (BNT162B2), on 05Apr2022 as dose 4 (booster), single (Lot number: FM0698) at the age of 65 years for covid-19 immunisation. The patient's relevant medical history was not reported. There were no concomitant medications. Vaccination history included: BNT162b2 (His vaccine card information is handwritten, and his first dose was 31Jan2021 of LOT: EL9261, NDC/EXP: not provided.), administration date: 31Jan2021, when the patient was 64-year-old, for COVID-19 immunization, reaction(s): "low iron"; BNT162b2 (Second dose was given 21Feb2021 with LOT: EN6200, NDC/EXP: not provided,), administration date: 21Feb2021, when the patient was 64-year-old, for COVID-19 immunization, reaction(s): "low iron"; BNT162b2 (First booster was 20Sep2021 of LOT: FF8841, no NDC/EXP provided.), administration date: 20Sep2021, when the patient was 64-year-old, for COVID-19 immunization, reaction(s): "low iron". The following information was reported: BLOOD IRON DECREASED (hospitalization, medically significant), outcome "unknown", described as "low iron"; HAEMOGLOBIN DECREASED (hospitalization, medically significant), outcome "unknown", described as "hemoglobin dropped". The patient was hospitalized for blood iron decreased, haemoglobin decreased (start date: 11Oct2022). The patient underwent the following laboratory tests and procedures: Blood iron: (unspecified date) Low; Haemoglobin: (unspecified date) 10.5, notes: dropped to 10.5 initially; (unspecified date) low, notes: it was so low; (10Oct2022) 5.9, notes: Result: 5.9; Unit: Not Provided. Therapeutic measures were taken as a result of blood iron decreased, haemoglobin decreased.  Clinical information: The patient said about Pfizer COVID-19 vaccine, the original one. He believed that there could be kind of a correlation with it after he had it well over a year ago now, within the last year or 11 months. He had been a normal 66 year old, a normal healthy guy, normal with no issues. Caller later clarified that his birthday was coming up and he was 65. He went to a routine checkup and didn't connect the two, went to a normal routine medical thing and they noticed his iron levels were very low. They have monitored those for a year and they are still low enough that he took over the counter iron supplements, and now he had also started getting iron infusions. His low iron levels corresponded to the time he started taking Pfizer COVID-19 vaccine, and he looked for medical information about this and didn't find anything concrete, which he was not saying that this happened because of Pfizer COVID-19 vaccine, but he did a generic search of the internet and found 100s of 100s of anecdotal stories saying the same thing happened to them within 30-45 days of the vaccine, they have depleted iron and doctors could not find out why their iron was depleted, and happened after Pfizer vaccination so he wanted to follow up and let people know, if Pfizer wanted to do an analysis after vaccination. Once his iron was gone, it was gone, he had to try to maintain it with over the the counter supplements etcetera. He wanted to see if Pfizer would look into this, all he had to do was google Pfizer vaccine and iron to definitely see literally hundreds say the same things, healthy fine males and females who can't pinpoint why their iron was suddenly depleted. No further details provided about males or females stories he found in his internet search. He says this started about 30-40 days after his first vaccine in Mar2021, and when they first started noticing they didn't correlate it with the vaccine. He doesn't know his iron level for that time. For treatment, they first started him on iron supplements over the counter, 36.5mg once a day. Now they have him on three times a day, after they had him on twice a day. He has been having low iron for a year, and his iron was so bad recently that he had to have infusions. He doesn't know the lab values for his low iron. For the last three months they have given him infusions along with the over the counter iron supplements, and Thursday is his 12th iron infusion, which will be done at the infusion lab. Iron infusion NDC/LOT/EXP: Unknown, not provided to him by the facility, when they do the iron infusion they just hang the bag and do the infusions, and don't give him medical information about it.   Investigations: Caller said the only other thing was that for the average male hemoglobin was supposed to be 13.5, and was dropped to 10.5 initially, so they were not overly worried, it was not good but it was not bad. This last week it dropped to half that and he was put in the hospital because it was so low. When your hemoglobin drops to 5, it is a deadly situation and can result in death, which 5.9 was his hemoglobin level. He was feeling really sick that day, and he called his doctor who wanted him to have blood tests done, that was on Monday. After she got the results, she called him at eight o'clock at night and told him to go to emergency room and have a blood transfusion. His hemoglobin was 5.9, which can result in major problems, and he spent a day and a half in the hospital getting blood transfusions. He clarifies that this was a week ago Monday, on 10Oct. He went to the hospital in the evening to the emergency room, where he was for four hours before they admitted him to the hospital on 11Oct at 01:00 AM, that was when they decided he had to have an infusion. He wanted to see if there was a known correlation or if Pfizer was aware of it. He would like to know does Pfizer have any information about low iron levels being associated with Pfizer COVID-19 vaccine.