Post‑vaccination Acute Pancreatitis in an Infant: A Report of a Rare Case and Brief Literature Review.

Acute pancreatitis (AP) is increasingly recognized in the pediatric population, although it remains uncommon in infants and young children. In this age group, diagnosis is often delayed because clinical manifestations, such as irritability, vomiting, and feeding intolerance, are nonspecific and may occur in the absence of classic abdominal pain. Most pediatric cases are mild and self‑limiting; however, severity can range from mild to severe depending on the presence and duration of organ dysfunction and the development of local or systemic complications at presentation.  A wide spectrum of etiologies has been described in pediatric AP, acute recurrent pancreatitis (ARP), and chronic pancreatitis (CP). However, vaccination is among the least frequently reported associations, with only isolated case reports in the literature. Establishing causality in such instances is challenging, and a thorough evaluation for more common etiologies remains essential. We report the case of a 12‑month‑old girl who developed AP three days after receiving the measles, mumps, and rubella (MMR) vaccine, which highlights the importance of maintaining a broad differential diagnosis.