headache; she had a mild soreness in her left arm after getting the COVID-19 Vaccine; This is a spontaneous report from a contactable pharmacist (patient) via a Pfizer-sponsored program Pfizer First Connect. This pharmacist reported similar events for two patients. This is the first of two reports. A 76-year-old female patient received first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE; Lot Number: EL1283) via an unspecified route of administration on 19Jan2021 10:30 AM at single dose on left arm for COVID-19 immunization. Medical history included temporomandibular joint (TMJ) pain in jaw and headache. Concomitant medication included Tylenol for temporomandibular joint (TMJ) pain in her jaw. The patient (retired pharmacist) stated that she and her husband got the COVID shot on Tuesday (19Jan2021) and prior to getting the vaccine, she was suffering temporomandibular joint (TMJ) pain in her jaw and took Tylenol that morning. Patient just came back from urgent care and was prescribed a dose pack of prednisone to take for 5 days for the TMJ and she is concerned about taking it because she knows it can suppress the immune system and she does not want to make the vaccine less effective. She was trying to figure out if she should just tough it out and not take the steroid. She and her husband, who was on warfarin, had a mild headache after the first shot but he has sinus issues and she had the TMJ, they were not sure if the headaches were from those things or the vaccine. Patient asked if she can take Tylenol since she found out that that may not have been a good idea. She was advised to take Prednisone and she was asking if she can take it or will it affect the efficacy of the vaccine. She stated not knowing that taking Tylenol can effect the efficacy of the COVID-19 Vaccine, she had taken Tylenol before she received her COVID-19 Vaccine on 19Jan2021 (Tuesday). Patient said her TMJ jaw pain was still a problem after she received her COVID-19 Vaccine, so she had gone to her doctor, and her doctor prescribed Prednisone, a corticosteroid. She said she was not going to take the Prednisone because she does not want the Prednisone to cause an issue with the efficacy of the COVID-19 Vaccine. Patient said she then read that studies performed on children said that children that took Tylenol did not get as good of an immune response from the COVID-19 Vaccine. Patient said since she already took a dose of Tylenol for her TMJ jaw pain before receiving her first COVID-19 Vaccine dose, she was afraid to take any further Tylenol. Patient clarified that the Tylenol she took was the generic Equate brand, 500mg. She said she took 2 Equate brand generic Tylenol 500mg for jaw pain on Tuesday morning (19Jan2021) prior to getting her first COVID-19 Vaccine. She said she had disposed of Equate brand generic Tylenol bottle and cannot provide the UPC, Lot and Expiration Date. Reported that both her and her husband did have a headache all day long after receiving the COVID-19 Vaccine. She said her husband believes his headache was from the COVID-19 Vaccine. She said she was not sure if her headache was from the COVID-19 Vaccine or from her TMJ jaw pain. She said when she has TMJ jaw pain, she usually has a headache accompanying the TMJ jaw pain. Also reported that she always gets her vaccines in her left arm. Patient was surprised she and her husband did not have anything more than a headache after receiving the COVID-19 Vaccine. She said when she had the Shingles Vaccine, she could not lay on her left side for a week because her arm was so sore for 2 days, and when she had the flu shot she could not get out of bed for a day. Patient clarified she got her first dose of the Shingrix Shingles Vaccine in Nov2020, and does not plan to go and get her second Shingrix dose until the summer of 2021. Patient stated that she does not want the second dose of the Shingrix Vaccine interfering with the COVID-19 Vaccine. The patient had headache on 19Jan2021, reported as mild. Patient also had a mild soreness in her left arm after getting the COVID-19 Vaccine on 19Jan2021, and the left arm soreness was gone in less than 24 hours. Patient further clarified that she had a headache before getting the COVID-19 Vaccine. She said her TMJ jaw pain acts up if she eats. She said when she has TMJ jaw pain, she gets an excruciating headache. She said she has no headache pain at all right no. Patient expected to have kind of a worse reaction to the COVID-19 Vaccine based on what other people have been saying. The events were assessed as non-serious. Outcome of the event headache and mild soreness in her left arm  was recovered in Jan2021. Patient does not think her headache pain was related to the COVID-19 Vaccine.; Sender's Comments: Based on the time association and drug's safety profile, the possible contribution of suspect vaccine BNT162B2 to the event headache cannot be totally excluded. The underlying temporomandibular joint and headache may be cofounders.,Linked Report(s) : US-PFIZER INC-2021082288 same drug/reporter, similar events, different patient