Arm hurt at the injection site; low grade fever; Caller stated that a severe allergic reaction is clearly defined.; This is a spontaneous report from a contactable consumer. This female consumer (Mother) reported for a 19-year-old male patient (Son) that, A 19-years-old male patient received BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Formulation: Solution for injection, Batch/Lot number: ER8729, Expiration date was unknown), via an unspecified route of administration in arm left on 07Apr2021 at 12:30 PM (at the age of 19-year-old) as a dose 1, single for COVID-19 immunization. The family medical history relevant to AE(s) was reported as none. The patient's medical history and concomitant medications were not reported. Prior vaccinations within 4 weeks were reported as none. History of all previous immunization with the Pfizer vaccine were reported as none. Additional vaccines administered on same date of the Pfizer suspect were reported as none. It was reported that, the reporter, (name) called on behalf of her son, (name) who had a low-grade fever last night after getting his first dose of the vaccine on 07Apr2021. (Name) also called to ask about what was the definition of fever like how many degrees and until when it will last. (Name) provided the second dose schedule of the vaccine of her son which was on 28Apr2021. Enquired, the reporter was called about her son, who was a patient received the first dose of the Pfizer covid 19 vaccine last Wednesday, on 07Apr2021 and has run a low grade fever since the second day of receiving the vaccine. Stated that, he has run a low grade fever throughout the whole 7 days. Stated that, his fever was 99.3 to 100.3 Fahrenheit and she was giving him Tylenol and Motrin. The reporter had questions pertaining to the low grade fever, stated that, how long should the low grade fever persist before it causes her concern. Should the patient go to the doctor about this low grade fever. If he was running a low grade fever, when he goes to get the second dose on 28Apr2021 can he still get the second dose. The reporter stated that, a severe allergic reaction was clearly defined on an unspecified date in 2021. Stated that, on day one, the patient did not have a reaction. On day two, the patient had a low grade fever. On day three, the patient's fever disappeared but his arm hurt at the injection site on an unspecified date in 2021. The reporter expected for patient's arm to hurt and the reporter did not think it was a big deal. On Friday night, 09Apr2021, the patient's low-grade fever came back. Stated that, the patient had a low grade fever for the next couple of days. Yesterday, on 13Apr2021, for most of the day, the patient had no fever, but it came back towards the afternoon. The reporter clarified that, it was not Friday that the low grade fever came back, it was either Saturday, 10Apr2021 or Sunday, 11Apr2021. Stated that, the reporter knows that, a low grade fever was a listed side effect of the covid vaccine. The reporter was asking what exact temperature would Pfizer consider a fever. The reporter was asking how long should the low grade fever be persistent before it started to cause concern. The reporter thinks he was very skinny. The patient did not have a primary care physician details. Stated that, low grade fever began evening of 08Apr2021. It was coming and going. The time that patient did not have a fever seems to be getting longer now. The reporter thinks that was a good thing. Stated that, the patient had no other problems and no allergies. The AE(s) did not require a visit to emergency room and physician office. The reporter was called today to see whether patient should go to a medical office. Treatment was received for the event low grade fever. On an unspecified date, the patient underwent lab tests and procedures which included temperature (body temperature), resulted as 99.3 Fahrenheit and 100.3 Fahrenheit. The outcome of the events for low grade fever was not recovered while for the other events was unknown.  No follow up attempts are possible. No further information is expected.