Cold and chill inside; Cold and chill inside; Bit headache; Sudden illness; Fatigue/tired; Chill inside; Low fever; Headache; Discomfort; Sudden illness; Cold and chill inside; No energy at all; Muscle pain on the left arm; Lost an appetite; This is a spontaneous report from a contactable physician. A patient of unspecified age and gender received second dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Formulation: Solution for injection, Lot Number: EW0185), via an unspecified route of administration, administered in Arm Left on 21May2021 11:54 as dose 2, single for covid-19 immunization at other. Medical history included, Allergy (dry eye and sinus infection) from an unknown date and unknown if ongoing. Concomitant medications included loratadine (CLARITIN [LORATADINE]) taken for an unspecified indication from May2021 to an unspecified stop date, steroid nasal spray (for about a week during the peak) and eyedrops to treat the eye inching and dry symptom taken for an unspecified indication from unspecified start and stop date. Family medical history relevant to adverse events were none. Patient did not take any medication after the adverse events. Historical vaccine included that patient received first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Formulation: Solution for injection, Lot Number: EW0171), via an unspecified route of administration, administered in Arm Left on 30Apr2021 as dose 1, single for covid-19 immunization. After the first dose patient had headache, discomfort, Flu-like symptoms, like fatigue, but did not take any medication. Mild symptoms resolved after rest and sleep. Patient did not take any medication 4 weeks prior to the first and second dose. Patient had a sudden and serious illness after 24hrs but recovered around 72hours till following Monday. The symptom was hard to describe. On Saturday 3pm, felt extremely tired, fatigue, chill inside, headache and had a bit temperature or low fever. In life, had never felt such ill, could not find the correct medical terminology to describe the clinical symptom, but felt extremely tired with no energy at all, even grabbing a cup of water seemed to take a lot of effort. Did not had the energy to walk downstairs. The entire body did not seem to belong to myself. Patient was trained as medical doctor with extensive experience in drug development and biomedical research. Patient knew that there was no medicine for this type of illness. So, patient did not call emergency, or take any medication. Also had muscle pain on the left arm for which the vaccine was administered (twice) but did not take pain killer or any medication whatsoever. Instead, took a hot bath, drunk tons of warm water with a bit salt, which helps increase the osmolarity in the blood stream. Went straight to the bed (semi-sleep), lying down around 3pm, and woke up at 9pm on Saturday Evening (22May2021), at that point, I felt slightly better, gained a bit more energy but was still very weak. Lost an appetite. Went back to sleep, woke up the next morning, by then felt a bit stronger, was able to walk downstairs for fresh air. The condition improved gradually, till Monday (24May2021), recovered with no chill, or fever, no headache, still a bit tire. 2.5 months later, on 11Aug2021, afternoon around 5-6pmEST, had experienced a very similar sudden illness, cold and chill inside, but moderate (less severe, short last) to what patient had on 22May2021 after the second dose. Patient put on two layers of clothing and went straight to the bed, had to use double bedding. Did not have fever this time, just cold, a bit headache. Woke up at 1:00am in the early morning (6 hours sleep), felt better, recovered from the chillness, and slept through till next morning waking up as normal. Reported to general physician. The difference between breakthrough infection and the vaccine AE seem to share a lot in common. On Monday August 16, I had COVID19 tests, rapid result showed positive and PCR result showed negative. Patient was waiting for the second PCR result to confirm the negativity now. Prior to the second dose during the week of May 16-20, 2021, had experienced a flu like symptom, very mild, felt a bit under weather, cold/chill, tired. Indeed, was hesitating to get the second shot on next day but woke up on Friday morning (May21) with good energy, and refreshing. So, decided to get the second shot. Suspect the adverse events related to could an infection prior to the second dose, vaccine dose interval was too close, 3 weeks apart, would it be dose related accumulative side effect. If we look at the adverse event profile overall, after the second dose, it triples the incidence rate: fever, chill and fatigue (>50-70%), which was very high, even it was mild. For your information, did not have a chronic condition that requires for medical treatment. Every spring had allergy (dry eye and sinus infection) during the flower blooming season around May time. This year patient took Claritin for 2-3 weeks in May (one tablet per day) and had an add-on of steroid nasal spray (sinus) for about a week during the peak. Used over the counter eyedrops to treat the eye inching and dry symptom (patient was eye doctor) about 6 weeks (May-early Jun). Patient was a bit over-weight according to CDC guideline (185 pounds/163 cm height). No Relevant tests. No treatment was received in result of events. The outcome of events fatigue, chills, fever, headache, illness, cold, muscle pain was resolved on 24May2021, discomfort, sudden illness, energy decreased, appetite lost was unknown, cold, headache, illness (second episode) was recovering, and chills (second episode) was resolved on 12Aug2021.  No follow-up attempts are possible. No further information is expected.