HCP calling to report an AE regarding the PROQUAD vaccine. HCP stated that an improperly stored PROQUAD was administered to a patient. HCP provided limited pertinent information and demographic data. Permission to follow-up with the HCP is unspecifie; No additional AE/PQC reported; This spontaneous report was received from a physician and refers to a 4-year-old male. No information on patient’s medical history, current conditions and concomitant medication was provided. On 30-DEC-2024, the patient was vaccinated with improperly stored dose (temperature excursion) of measles, mumps, rubella and varicella (oka-merck) virus vaccine live (PROQUAD) Subcutaneous Injection (albumin status: rHA) lot #Y009108, expiration date: 06-NOV-2025, administered subcutaneously in the left arm for prophylaxis (strength, exact dose, and dose number were not provided) (product storage error). The vaccine was determined to be viable. No additional adverse events and product quality complaints was reported (no adverse event).