not quite IM in the Deltoid, it was potentially located more towards the elbow; chills; I felt a little off; local reaction with redness at the site of the injection; local reaction with redness at the site of the injection; it felt hot; she received her booster dose, 3rd dose, of the Pfizer COVID19 Vaccine; she received her booster dose, 3rd dose, of the Pfizer COVID19 Vaccine; This is a spontaneous report from a contactable pharmacist (patient son), from Pfizer medical information team. A 65-year-old female patient (nurse) received third dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, formulation: solution for injection, lot number was not reported, expiration date was not reported), via an unspecified route of administration on 17Sep2021 as dose 3 (Booster), single for covid-19 immunization. The patient medical history and concomitant medications were not reported. The patient historical vaccine included second dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, formulation: solution for injection, lot number was not reported, expiration date was not reported), received via an unspecified route of administration on Jan2021 as dose 2, single for COVID-19 immunization. It was reported that, the pharmacist, calling on behalf of his mother, also on the line and also a RN, states she received her booster dose, 3rd dose, of the Pfizer COVID19 Vaccine 17SEP2021 and they have concerns that the vaccine was given in the wrong region of the arm. The reporter states that the injection was given not quite IM in the Deltoid, it was potentially located more towards the elbow. Patient states that it was given too low and was mid way from her acromial process and elbow, given at 90 degree angle. May have hit a muscle; it was bicep or tricep. The patient is a 65 year old female who is school nurse and fighting it everyday out there. Each of the reporters, the patient and the son have read the CDC document regarding not having to repeat dose and potential worsening local or systemic side effects, they state they hope it still as effective. Reporter wants to know if her booster dose is effective enough to really have boosted her immunity since she had 2nd dose 8 months ago. The reporter does report also his mother having systemic side effects, chills and some redness but that is all he states. The son saw a picture of it. The patient states that she did have a local reaction with redness at the site of the injection. Started and it felt hot like any other reaction to an IM injection and it was low. she knew where the Band-Aid was placed, she thought it was a little low and the redness really made me think it was low. Patient further states that the next day, she felt a little off. Maybe she did get a dose of it in the IM. Like she said, she dont know... she dont think it went in the deltoid at all, if so it went bicep or tricep. Reporter was hoping to get something regarding efficacy but states obviously information is not known. The reporter states he is speculating but hoping she has some immune response but unable to back this up with data as he is speaking to his mother during the call.  The patient states she did report it to the pharmacy to have them enter into the VAERS database as a vaccine error because she felt it was or she wouldn't have perused it. The reporters are calling today to see if we have any clinical data for potential wrong route of administration and the efficacy of the product thereafter such an event. The outcome of the events was unknown.  Batch/lot number not reported it will be requested during follow-up activities.