the patient had experienced any adverse issues or side effects from the administrations; a patient (15-month-old boy) who is otherwise healthy was inadvertently administered a dose of PROQUAD and VARIVAX by his medical assistant (MA) instead of a dose of MMR II and VARIVAX that was ordered and prescribed by the HCP on 01/15/2025.; a patient (15-month-old boy) who is otherwise healthy was inadvertently administered a dose of PROQUAD and VARIVAX by his medical assistant (MA) instead of a dose of MMR II and VARIVAX that was ordered and prescribed by the HCP on 01/15/2025.; This spontaneous report was received from a nurse practitioner referring to a 15-month-old male patient. The patient’s medical history and concurrent conditions were not reported. On 15-JAN-2025, the patient who was otherwise healthy was inadvertently administered a dose of measles, mumps, rubella and varicella (oka-merck) virus vaccine live (recombinant Human albumin [rHA]) (PROQUAD) injection, 0.5ml / once, lot #Y012594, expiration date: 14-JAN-2026, administered for prophylaxis (strength, and route of administration were not provided); and varicella virus vaccine live (oka/merck) (VARIVAX) injection, 0.5ml / once, lot #Y011017, expiration date: 18-JUN-2026, administered for prophylaxis (strength, and route of administration were not provided); along with sterile diluent (BAXTER STERILE DILUENT) solution for injection/infusion, lot #1973283, expiration date: 08-OCT-2026 (strength, dose, route of administration, and indication were not provided) by his medical assistant (MA) (operator of device: health professional) instead of a dose of measles, mumps, and rubella (wistar ra 27-3) virus vaccine, live (M-M-R II) injection (administered for prophylaxis, dose, strength, lot #, expiry date, and route of administration were not provided) and varicella virus vaccine live (oka/merck) (VARIVAX) that was ordered and prescribed by the health care professional (HCP) (Wrong product administered and Accidental overdose). The HCP stated he called to check on the patient on the evening on that day after the administration who was “doing well” and the parents did not report the patient had experienced any adverse issues or side effects from the administrations (No adverse event). No other information provided during the call.