Female 15-year old client received her first Pfizer shot (Lot# EW0185) at 15:02. She was accompanied by her mother and 12-year-old sister, who was also vaccinated at the same station with her. Client received her shot first and waited while her sister received her shot. After both girls were vaccinated, they were walking with their mother down the hallway to the observation room. RN1 stated that from the opposite end of the hallway she saw client?s knees buckle. RN1 walked toward client to ask if she was OK. Client straightened herself out, slumped onto her mother?s shoulder, and rolled onto her mother, who guided client to the floor. At 15:09 Lead RN heard client fall to the floor, went out to the client, and radioed for EMT assistance. Client was conscious and turned her face up. Client?s mother stated client passed out for 2-3 seconds and that her head did not hit the floor. Client?s mother stated that she cushioned her fall. Client was breathing adequately, appeared pale in face and lips, and stated she was OK. Lead RN and RN1 kept client lying on the floor and elevated her legs on a chair. EMT1 & EMT2 arrived at 15:10 and checked client?s pulse (HR: 74). Client denied head, neck, and back pain. Client was alert & oriented times 3 (person, place, & event). Client stated she was OK to stand up and sit in a wheelchair. Wheeled client to extra vacant breakroom where client vitals were taken by EMT2 at 15:17 (BP: 124/60, HR: 96). EMT1?s assessment found the client exhibited good circulation, sensation, and motor function in all 4 extremities. Client denied chest pain, shortness of breath, and nausea & vomiting. Client was leaning forward in the wheelchair resting her elbows on her lap. She stated she does not remember becoming nonresponsive and that she felt dizzy when lying her head back. Client stated she has a history of anxiety and panic attacks and is currently taking Prozac. Client stated she felt hot. Client?s mother stated client ate a full lunch at 12:35. At 15:20 Lead RN provided client with a bottle of water. Lead RN & EMT also observed client?s color returning to her face at that time. Client sat upright and stated that she felt better and was alert & oriented times 4. Client and mother declined going to the hospital and calling 911 for evaluation. At 15:23 client was wheeled to the observation room with her mother and sister where she remained seated in the wheelchair for 30 minutes for additional observation by EMT1. At 1600 EMT1 took client vitals while she was seated (BP: 116/82, HR: 68, RR: 16). EMT1 took client vitals again while having client stand (BP: 120/86, HR: 72, RR: 16). Client and mother stated they were OK to go home. Client and mother were instructed by Lead RN to follow up with HCP if client experienced any additional symptoms after going home and to call 911 if client experienced SOB or any difficulties breathing. Lead RN and EMT observed client leave the facility walking with a steady gait with her mother and sister.