Flare of her RA/ rheumatoid arthritis really got bad and painful in joints; This is a spontaneous report from a contactable consumer (patient). A 77-year-old female patient received first dose of BNT162b2 (PFIZER BIONTECH COVID-19 mRNA VACCINE, Solution for injection, Lot number- EM9809) via an unspecified route of administration in left arm on 04Feb2021 at 12:30 as dose 1 single (at the age of 77-year-old) and also received second dose of BNT162b2 (PFIZER BIONTECH COVID-19 mRNA VACCINE, Solution for injection, Lot number- EN6200) via an unspecified route of administration in left arm on 25Feb2021 at 14:00 as dose 2 single (at the age of 77-year-old) for COVID-19 immunization. Medical history included illness at time of vaccination, rheumatoid arthritis, blood pressure, cholesterol, occasional spastic bowel, blood type: Rh-Negative. No investigation assessment was reported. History of all previous immunization with the Pfizer vaccine considered as suspect, additional vaccines administered on same date of the Pfizer suspect, prior vaccinations (within 4 weeks), adverse events following prior vaccinations, family medical history relevant to adverse event were reported as none. Concomitant medications included methotrexate 2.5 mg, weekly (2.5 mg tablets orally. Takes 9 tablets by mouth once a week) for Rheumatoid arthritis from 23 years, atorvastatin 40 mg, daily for Cholesterol (had been taking 10-15 years), atenolol 25 mg, daily for Blood pressure (Had been taking 10-15 years), hydrochlorothiazide, triamterene (TRIAMTERENE & HCTZ) daily (37.5/25 mg) for fluid retention and blood pressure (Had been taking 10-15 years). The patient experienced flare of rheumatoid arthritis, it really got bad and pain in joints lasted about 5 weeks before she contacted the rheumatologist, started around 17Feb2021 or 18Feb2021 and had subsided. She had flares on occasions and when agent asked her about documenting the experience, she added that there was no way to be proven whether it was due to the shot or that she came off her medication. Patient stated it subsided within a couple days of going on the prednisone, some time in Apr2021. Patient stated it took about six weeks to get back.  Patient stated she had both vaccine shots from Pfizer back in Feb2021 and a couple weeks ago, she heard on the news, and some friends have told her about it since, and she did check it out online, that a study was done at the same time, on the effectiveness of the Pfizer vaccine on patients who had been on methotrexate. Patient stated the findings were that those patients, in four control groups, were 62% covered on the vaccine versus the 95%. Patient added that means some were above 62%, and some were below. Patient stated she was curious because she's been on methotrexate for 23 years, she did stop it the week before and after each shot. Patient asked was there any way of finding out her own personal protection. Patient stated she did call her doctor about antibody testing, and the doctor told her she was not sure what it would show her, since she's not under a controlled situation, with exact dates that she stopped taking and retook it, also she had a flare at that time, about two weeks after the shot, where her rheumatoid arthritis really got bad and painful in joints. Patient stated it took about six weeks to get back. Patient stated she would have the flares on occasions anyway. Patient clarified this was not why she called and adds that when she mentioned it to her rheumatologist, she was told insurance would not cover it because she was not classified under any research program. Patient stated she did not go to the doctor, she suffered with it until her primary said call your doctor, call you rheumatologist for the pain. Did not go to the doctor, only called because it was covid time and everything was either via phone or video. Stated her rheumatologist has known her long enough to feel safe diagnosing. Not required to visit Emergency Room and Physician Office. Patient again stated she was not sure the event reported was from the vaccine. Patient reported an AE/PC for Methotrexate reports she's been on methotrexate for 23 years, she did stop it the week before and after each shot. Patient stated she would have the flares on occasions anyway. Relevant tests were reported as none. Product strength and count size dispensed: 2.5 mg tablets. Treatment medication included Prednisone: 5 mg tablets, started with four tablets once a day for two days, then three tablets for two days, then two tablets once a day for two days, then one tablet once a day for two days. Took a total of eight days. The outcome of the event was recovered in Apr2021.   Information on the lot/batch was available, Additional information has been requested.