reactive arthritis; lethargic; 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.  A 55-year-old male patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), on 03Nov2022 as dose 4 (booster), single (Lot number: GJ6665) at the age of 55 years, in left arm for covid-19 immunisation. The patient had no relevant medical history. There were no concomitant medications. Vaccination history included: Bnt162b2 (DOSE 1, SINGLE), administration date: 2021, for COVID-19 immunization, reaction(s): "No adverse event"; Bnt162b2 (DOSE 2, SINGLE), administration date: 2021, for COVID-19 immunization, reaction(s): "No adverse event"; Bnt162b2 (DOSE 3 (BOOSTER), SINGLE), administration date: Oct2021, for COVID-19 immunization, reaction(s): "No adverse event". The following information was reported: LETHARGY (non-serious) with onset 03Nov2022, outcome "not recovered", described as "lethargic"; ARTHRITIS REACTIVE (medically significant) with onset Dec2022, outcome "not recovered", described as "reactive arthritis". Therapeutic measures were taken as a result of arthritis reactive, lethargy. Clinical course: Patient called about the Pfizer Bivalent. He got the vaccine on 03Nov2022 and had done very well with all Pfizer vaccines. "Is heavily and has been vaccinated beyond that". A week after the Pfizer Bivalent he was very tired and lethargic which turned into arthritis. He has worked through two medical systems to get a solid diagnosis. Patient was waiting for a rheumatology appointment in Sep2023. He lives in the country with their rheumatology. Had a DMAD, a disease modifying anti rheumatic drug. First one was Methotrexate and the second one was Leflunomide. Arthritis reaction he got has been substantial. Did internet reading and a few articles are coming out about mRNA causing arthritis. He wanted to know if Pfizer had a consultant that he could speak with to help gather information about how to deal with this. This has been a life changing event. He had the initial Covid vaccine and booster back in 2021. Later in Oct2021 had the follow up and the year after that in Nov2022 had the Pfizer Bivalent. He did not have problems with other three. Bivalent in Nov2022 hit him much harder than the other three. Clarified that he had Pfizer Bivalent on 03Nov2022. Clarified that he was on the drugs Methotrexate and Leflunomide after the Pfizer Bivalent vaccine. Started Methotrexate in 18Feb2023, 15mg oral once a week and discontinued it in Apr2023. Started Leflunomide tablet in May2023, 20mg oral once a day and discontinued it in 14Jun2023 because both made him very sick. Patient was very tired since 03Nov2022 and is ongoing and consistently getting worst. Patient was also lethargic since 03Nov2022 and is ongoing since the day of vaccine which is the same or worst. Reactive arthritis/joint pain started in mid Dec2022 was described as getting joint swelling and increased joint pain on his both hips especially right hip, both knees especially the left knee, ankles, knuckles in hand at first joint all way across four fingers, both wrists, his spine both thoracic, lumbar and cervical and general body aches throughout everywhere. Both knees swollen and left knee twice normal size and had pitting edema below the knees down to his ankles. Maximum or worst of that was late January or early February and he was able to see a house doctor. Is consistently getting worst.  Patient was trying to get reactive arthritis under control with Methotrexate and Leflunomide. Patient was also treated with a nonsteroidal that is a Cox 2 inhibitor called Etoricoxib. Initial treatment for joint swelling was Prednisone. Pitting edema below the knees down to his ankles was resolved completely with Prednisone treatment in late Jan2023. Patient was also t4reated with Ibuprofen 600 mg oral twice a day on 17Feb2023 for aches and pains, edema, and joint swelling.