No appetite; headache; Nauseous; achy/aching/Arm blew up like a baseball; not feeling well (flu like); not feeling well (flu like); swollen arm; she felt a little tired; She can hardly lift her head to the pillow; not feeling for 2 days; sore arm; This is a spontaneous report received from a contactable reporter(s) (Other HCP) from medical information team for a Pfizer sponsored program. The reporter is the patient.  A 74 year-old female patient received bnt162b2 (BNT162B2), administered in deltoid left, administration date 30Sep2021 16:00 (Lot number: EW0185) at the age of 74 years as dose 3 (booster), single for covid-19 immunisation. The patient's relevant medical history was not reported. There were no concomitant medications. Vaccination history included: Bnt162b2 (DOSE 1, SINGLE, Lot: EJL685, Expiry/NDC: Unknown.), administration date: 22Dec2020, when the patient was 73 years old, for covid-19 immunization, reaction(s): "her arm was sore", "she felt tired", "achy"; Bnt162b2 (DOSE 2, SINGLE, Lot: EL3248 , Expiry/NDC: Unknown.), administration date: 12Jan2021, when the patient was 73 years old, for covid-19 immunization, reaction(s): "her arm was sore"; Bnt162b2 (DOSE 2, SINGLE, Lot: EL3248 , Expiry/NDC: Unknown.), administration date: 12Jan2021, when the patient was 73 years old, for COVID-19 immunization, reaction(s): "she felt tired", "achy". The following information was reported: PAIN IN EXTREMITY (non-serious) with onset 2021, outcome "unknown", described as "sore arm"; PAIN (non-serious) with onset 30Sep2021, outcome "recovered" (02Oct2021), described as "achy/aching/Arm blew up like a baseball"; MALAISE (non-serious), INFLUENZA LIKE ILLNESS (non-serious) all with onset 2021, outcome "unknown" and all described as "not feeling well (flu like)"; PERIPHERAL SWELLING (non-serious) with onset 2021, outcome "unknown", described as "swollen arm"; DECREASED APPETITE (non-serious) with onset 01Oct2021, outcome "recovered" (02Oct2021), described as "No appetite"; HEADACHE (non-serious) with onset 30Sep2021, outcome "recovered" (01Oct2021), described as "headache"; FEELING ABNORMAL (non-serious) with onset 2021, outcome "unknown", described as "not feeling for 2 days"; NAUSEA (non-serious) with onset 30Sep2021, outcome "recovered" (02Oct2021), described as "Nauseous"; FATIGUE (non-serious) with onset 2021, outcome "unknown", described as "she felt a little tired"; ASTHENIA (non-serious) with onset 2021, outcome "unknown", described as "She can hardly lift her head to the pillow". Therapeutic measures were taken as a result of headache.  Additional information: Prior Vaccinations (within 4 weeks) If applicable, list any other vaccinations within four weeks prior to the first administration date of the suspect vaccine(s) and AE(s) following prior vaccinations: None. Patient's Medical History (including any illness at time of vaccination) and Family Medical History Relevant to AE(s): None. Relevant Tests: None. Additional Vaccines Administered on Same Date of the Pfizer Suspect If applicable, list all vaccines administered on same date with the Pfizer vaccine considered as suspect: None. . History of all previous immunization with the Pfizer vaccine considered as suspect (or patient age at first and subsequent immunizations if dates of birth or immunizations are not available): 1st dose received on 22Dec2020. Lot: EJL685, Expiry/NDC: Unknown.2nd dose received on 12Jan2021. Lot: EL3248, Expiry/NDC: Unknown.Caller clarified that her 1st dose was in Dec, 2nd dose was in Jan, and 3rd dose was on 30Sep2021. Per caller her secondary symptoms were sore arm, achy, not feeling well (flu like). Caller voiced the reactions from the booster vaccine put her on the couch with swollen arm, no appetite, headache, aching, and not feeling for 2 days. She received the booster at 4:00 pm and the symptoms started around 11:30pm or 12 am. The following day she took one Excedrin for the headache. Caller asking if the Pfizer Covid 19 Booster Vaccine was different from the two dose series, that would have lead us to react more stronger. was it a different chemical compound, or because her immune system lowered over a 9 month period. Caller mentioned she did not take any medication before receiving her booster dose, and this reaction seemed much stronger that with her previous doses. Caller has several different questions. was the booster dose a different preparation; was it stronger or weaker that the other doses. She wants to understand the severity of the reaction; was it because the doses were so far apart. She wants to understand if taking over the counter medication was recommended prior to getting the vaccine. Caller asking if Pfizer has information regarding waiting 4 weeks in between other vaccines and the Pfizer Covid 19 Vaccine. Per caller I seen it recommend to tell people to try Pedialyte when getting the symptoms of the post booster (Pfizer Covid 19). Caller asking if Pfizer has information on this. States that she got her 3rd dose around 4pm on 30Sep2021 and noticed all the reactions beginning around 11:30pm-midnight. Arm blew up like a baseball: This diminished over the 1st and was hardly noticeable, by the 2nd it was gone. States yesterday she felt a little tired, but it may be because she didn't drink enough fluid. Headache: She took 1 Excedrin on 01Oct2021 in the afternoon when she was sure that she wouldn't throw up and the headache went away. No appetite: She didn't really want to eat, but she ate on 02Oct2021. She hydrated on the 1st and forced herself to eat on the 2nd. States that she did not lose her sense of taste, just her appetite. Nauseous: It wasn't so bad that she couldn't eat, but when she didn't eat, it just didn't taste quite the same. States that she knows something is off if she doesn't like the taste of milk, but states that the taste of other foods wasn't off. States that she felt horrible for 2 days, but luckily she was off work. She had been told to get the vaccine before scheduled days off so that's what she did. She was waiting until the end of the month to get the flu shot even though she was told that she could get the flu shot and the covid 19 vaccine together. States that the side effects with the first 2 doses were similar. After the 1st dose, her arm was sore and she felt tired and achy. After the 2nd dose, her arm was more sore than after the 1st dose, and she felt more tired and achy than after the first one. States that those reactions only lasted 1 day. Adverse events did not result in Emergency or physician office visit. The caller wants to know if a "half dose of the booster of Pfizer COVID Vaccine was recommended now. She heard this on the news, unsure of where it came from or if its even true. She mentioned it may be having been from the CDC. This can be very misleading if a full dose is what is recommended." After guidance was provided the caller states "Thank you. Caller would like to know "why some of us were having much stronger of a reaction to the booster. It was not age related. Meaning the nurses she work that were between young 30s and older that were having same or similar reactions. Her reaction was a doozie. The caller wants to know was it because the last vaccine many of them got was in January and they just got the booster end of September beginning of October. Could it be that the immune system dropped off. . The information provided from the document is on label and noted.Is the half dose booster safer than the full dose booster. There were quite a number of nurses she works with that had pretty strong reactions to it. she asked the question, could it possibly be because many of them with the more severe reactions had the last vaccine in Jan2021 because it was not okayed until recently for the booster. Caller stated: "It's not just her. She was an ICU nurse and one unit manager told her fifteen people called out because of that kind of reaction." and that Caller did not take any medications prior to taking the booster. Other Products, Patient History and Investigation Assessment was reported as no.  No follow-up attempts are possible. No further information is expected.