some possible increase in heat exhaustion; kind of like a heat stroke; This is a spontaneous report from a Pfizer sponsored program . This case is for 1 of 4 patient whose demographic was available.  A contactable (Physician) reported that a 24-year-old male patient received bnt162b2 (BNT162B2, Solution for injection, Lot: EW0180) via deltoid alternating on 02Jun2021 (at the age of 24-year-old) at 08:00 as single dose for COVID-19 immunization/ Health force protection. Medical history and concomitant medications were not reported. The patient historical vaccine reported was bnt162b2 (Lot: unknown) via deltoid alternating on 10May2021 (at the age of 24-year-old) at 06:54 as single dose for COVID-19 immunisation. The patient was in the emergency room and discharged from the emergency room. No history of allergic reaction to any kind of vaccines was reported. Caller was a military physician and had reported some of his men (referring to military people) were actually experiencing some difficulty in carrying out their usual military exercises as compared to before. He mentioned some possible increase in heat exhaustion, but he is not positive that it is caused by the vaccine. In line with this, he would like to have some information in regards precaution that may be aware of regarding an increase in heat exhaustion after "x" amount of days after getting the vaccine. Over-all there were 28 people reporting this side effect after getting their second dose on 06Jun2021. A bunch of other factors probably played a role. Kind of chasing a wild goose. The caller wanted to make sure. The caller reported he has not seen anything else in his research other than a couple reports of pericarditis in young men. The caller wants to make sure there is no reason to be concerned. The caller states the event was probably heat and humidity related issue, peoples conditioning. The caller was the officer assigned to investigate the situation. The caller wanted to make sure he was not missing anything and was doing his due diligence. The caller would like to know any recommendations, the caller stated he has not seen taking it easy for longer than a week or two after receiving the Pfizer Covid Vaccine. The caller stated part of the exercises was the 12-mile march, part of exercises called EID, a bunch of tasks the persons perform. During the 12-mile March 28 folks kind of fell out with heat exhaustion. Generally speaking, with this kind of exaggerated heat exhaustion, to have 28 persons experience was a large number for the caller. The caller states this has gone away for the patient after the patient was discharged from the emergency room. The patient was doing fine. The caller stated the patient has recovered completely. The caller stated he feels pretty good about doing the Pfizer Covid Vaccines every 3-4 weeks in terms of once a person starts the Pfizer Covid Vaccines. The patient had elevated CK that went all the way up to 1,683. The patient had an AKI of 2.2, creatinine of 2.2, normalized on 15Jun2021 back down to 1.1. The CK down trending by 17Jun2021. Outcome of the events was recovered on an unspecified date in Jun2021.  Causality: The caller stated the event was not a direct correlation, more of an indirect kind of thing that just popped up. Whether the event is a thing or more of like, a bunch of other reasons the caller can think of that this could happen including heat and humidity.   Information on the lot/batch number is available. Other information is expected.; Sender's Comments: Based on the information provide in the narrative, the causal association between the suspect drug and the events 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.,Linked Report(s) : US-PFIZER INC-2021755866 Same reporter/ drug/ AE, different patient