Premature infants should be immunized according to their

• A. Corrected age
• B. Gestational age
• C. Postnatal age
• D. Chronologic age

Answer: (D)

Premature infants receive vaccines based on their chronological (postnatal) age. This means the timing of each dose follows how many days, weeks, or months have passed since birth, not how far along they were in gestation. Using chronological age ensures protection aligns with the period of greatest exposure risk and with the immune responses studied in vaccine trials. Corrected age is used for growth and developmental assessments, not for scheduling vaccines. In practice, a preterm infant gets vaccines at the same chronological ages as a term infant, provided they are clinically stable; delays are only appropriate if the infant is acutely ill orunstable.