Legs are giving out on me; Feeling very brain foggy; Actually interfering with my job; it is like I am in a zone, I hear what she says and then I don't even remember; weird leg cramps; Actually interfering with my job; it is like I am in a zone, I hear what she says and then I don't even remember; weird leg cramps/short pain; I did get the Pfizer instead of the Moderna this time because I got really sick with the Moderna; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 34-year-old female patient received BNT162b2 (BNT162B2), on 26Jul2022 as dose number unknown (booster), single (Lot number: FM0173) at the age of 34 years for covid-19 immunisation. The patient's relevant medical history was not reported. Concomitant medication(s) included: VITAMINS NOS; FISH OIL; IRON. Vaccination history included: Moderna, administration date: 2021, for covid 19 immunization, reaction(s): "got really sick ". The following information was reported: INTERCHANGE OF VACCINE PRODUCTS (non-serious) with onset 2022, outcome "unknown", described as "I did get the Pfizer instead of the Moderna this time because I got really sick with the Moderna"; IMPAIRED WORK ABILITY (non-serious), MEMORY IMPAIRMENT (non-serious) all with onset Aug2022, outcome "unknown" and all described as "Actually interfering with my job; it is like I am in a zone, I hear what she says and then I don't even remember"; FEELING ABNORMAL (non-serious) with onset Aug2022, outcome "unknown", described as "Feeling very brain foggy"; LIMB DISCOMFORT (non-serious) with onset Aug2022, outcome "unknown", described as "Legs are giving out on me"; MUSCLE SPASMS (non-serious) with onset Aug2022, outcome "unknown", described as "weird leg cramps"; PAIN IN EXTREMITY (non-serious) with onset Aug2022, outcome "unknown", described as "weird leg cramps/short pain". Therapeutic measures were not taken as a result of limb discomfort, feeling abnormal, impaired work ability, muscle spasms, memory impairment, pain in extremity.  Additional information: Patient stated, "The reason for my call ma'am, I just got done reaching out to the pharmacy and I am going to be honest with you, I don't know if it is from the vaccine. I know that I for sure that I do not have COVID, but I have noticed, I got my Pfizer last month at the end of the month. I believe it was 24Jul, I am not exact, but I did get the Pfizer instead of the Moderna this time because I got really sick with the Moderna, but I have been noticing, I have been having like weird leg cramps. They kind of come like a short pain, like come and go. It is like throughout the day and sometimes I am still like my legs are giving out on me since I got that booster, and I don't know if it just me in my head over thinking. I find it a little concerning. I never had this problem before. I am fairly young, I am only 34 years old, and I have been noticing this since, I got my Pfizer. So, I am not sure if this is a common side effects that people have been reporting but I also do feel I have been feeling very brain foggy since I got the vaccine too." Patient stated, "Yes, it is actually interfering with my job. I have been noticing it like throughout the day at work. There is sometimes like, I will be talking to my boss and I just totally, it is like, I am in a zone, I hear what she says and then I don't even remember, and I have been noticing this since I got the booster, and I did wait quite some time since I got my Moderna. It has been almost over a year." Patient started noticing side effects about two weeks after the vaccination. Any prior vaccinations (within 4 weeks): Patient stated, "No, I have only been waiting to get my flu shot until October."