Fever; Severe headache; Felt really painful; 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 18-year-old female patient received bnt162b2 (BNT162B2), administration date 30Sep2021 (Batch/Lot number: unknown) as dose 3 (booster), single for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Sinovac vaccine (received the Sinovac vaccine series in country back in July), administration date: Jul2021, when the patient was 18 years old, for COVID-19 Immunization; Sinovac vaccine, for COVID-19 Immunization. The following information was reported: PYREXIA (non-serious) with onset 2021, outcome "unknown", described as "Fever"; HEADACHE (non-serious) with onset 2021, outcome "unknown", described as "Severe headache"; PAIN (non-serious) with onset 2021, outcome "unknown", described as "Felt really painful".  Additional information: Caller is an 18-year-old patient who previously received the Sinovac vaccine series in country back in July. She is here in the country as a student and on 30Sep2021, received the 1st dose of the Pfizer Covid vaccine. Caller reports "severe headache and a fever the day after receiving the shot". Caller wants to know if it is okay to receive the second dose of the Pfizer Covid vaccine. Informed caller that Headache and Fever are side effects that have been reported after taking the Pfizer Covid vaccine. Also: As noted in the Fact Sheet for Recipients, you should not get the Pfizer-BioNTech COVID-19 Vaccine if you had a severe allergic reaction after a previous dose of the vaccine or if you had a severe allergic reaction to any ingredient of the vaccine. The decision to receive the second dose for any other reason cannot be made by Pfizer. We refer you to speak to your healthcare provider about the risks of the vaccine compared to the risks of potentially not being fully protected against COVID-19 infection. Your healthcare provider knows your health situation and has access to information that can better help inform this decision. Reason for no lot number: of Covid 19 vaccine: Other: LOT#: Consumer stated, "I don't have it with me now. I am outside." Transferring agent stated, " I have a consumer who is reporting a terrible headache and fever after receiving the Pfizer Covid19 vaccine. She received the Pfizer first dose. She is from withheld. She received the Sinovac vaccine in withheld, came to the country, sometime this summer and received the first dose Pfizer Covid19 vaccine (Further clarification unknown. Hence, captured as event conservatively.) on 30Sep2021. As I said day after she received the vaccine, she had terrible headache and fever that day, the day after. She is 18 years old, and I already answered her question regarding whether not she should get the next dose. I referred her to the health care provider." When informed about the role of Pfizer Drug Safety and about Medical Information Department for the concern, consumer further stated, "Okay, but they told me because they connected me to you and said you will give me the suggestion." Consumer stated, "My question is, because I am fully vaccinated in withheld (further clarification unknown), I had the two doses of Sinovac (Unspecified Medication) but after I arrived in the country, I completed all my doses in withheld in Jul the 2nd (not clarified) and now, I had the fresh one given. So, on the last day of Sep, I had the first dose of Pfizer, but I was very, I had a very terrible headache and felt painful after that, and I had a fever for a day long. So, now I can have the second dose, but I am worrying maybe if I will feel more terrible after I had the second dose and should I have the second dose because of my (sentence incomplete)?" (Name for Sinovac not clarified, hence suspect captured as Unspecified Medication). Further probing could not be done as consumer was unwilling to share any further information. Hence, product details purchase details and other details were unknown and limited information was available over the call.  QR Comment: -Country of Incidence could not be clarified further, hence captured as-private by default  Follow-up attempts completed. No further information is expected.