Heat exhaustion; He got sick during the night; Sore arm; This is a spontaneous report from a contactable nurse. This case refers to the first vaccination of two vaccines. A 15-year-old male patient received first dose of BNT162B2 (COMIRNATY, Solution for injection, LOT number: ER8733 and expiration date was not provided), via an unspecified route of administration, in the left arm on 27May2021 at 14:00 (at the age of 15-yaer-old) as single dose for COVID-19 immunization. Medical history included Lyme's disease from 04Jul2020 (reporter said it was also called Anaplasmosis and Tick Bite Disease. It was treated with antibiotics and then that was it. A recheck showed nothing), ongoing High Level Autism Spectrum from 2008, ongoing Vitamin D decreased from on an unknown date in Aug2019 to 02Jun2021 (He had it about 9 months ago when reporter took him for his school physical, clarified it was Aug2019 and ongoing difficulty getting to sleep. Patient had high level on the autism spectrum. His last labs come back normal, so he did not have to take Vitamin D anymore. Patient did not have any family medical history relevant to AEs. Concomitant medications included ongoing melatonin (strength: 10 mg) at 10 mg once a day (every night) for difficulty getting to sleep (taking for about 4 months) and ongoing VITAMIN D NOS for VITAMIN D decreased (His Vitamin D had been low, and he had been taking Vitamin D). Patient experienced sore arm on 28May2021 (after first vaccine). Patient had Heat exhaustion (10 days ago) and got sick during the night on an unspecified date in Jun2021. Reporter stated the sore arm was completely resolved. He got sick during the night and he was taken to the emergency room. He had 2 bags of fluids and supposed that was 2 liters. He was ok after that. Patient was required a visit to emergency room for events Heat exhaustion and got sick during the night. Patient was very careful. He wore a mask. He washed his hands and used hand sanitizer. No additional vaccines administered on same date of the Pfizer suspect. The patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. His last physical was on 02Jun2021, he had his blood drawn and it came back within normal limits. Seriousness of the event Sore arm was reported as non-serious and for other events it was not reported. Outcome of the event sore arm after first dose was recovered on an unknown date in 2021 and outcome of the other events was recovered in unknown date in Jun2021. Reporter stated that Pfizer Covid-19 Vaccine was related to Sore arm (first dose).  Information on lot/batch number was available. Additional information has been requested.; Sender's Comments: Based on the reported information, a causal association between the reported events of heat exhaustion, illness and suspect drug bnt162b2 cannot be excluded. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.