The parent of a 6-week-old preterm infant asks about the timing of the first dose of Infanrix (DTPa-Hib-IPV-HepB). Select the most appropriate age for immunisation.

• A. 6 weeks
• B. 8 weeks
• C. 12 weeks
• D. 16 weeks

Answer: (B)

Vaccination timing for infants is based on chronological age, not corrected gestational age, and vaccines are given when the baby is well enough. Infanrix (DTPa-Hib-IPV-HepB) is typically given as a primary series starting at eight weeks of age, with subsequent doses at twelve and sixteen weeks. For a six-week-old preterm infant, the first dose should be given when they reach eight weeks of age, assuming there are no contraindications. Giving at six weeks would be earlier than recommended, while starting later than eight weeks would delay the series. So the most appropriate age to administer the first dose is eight weeks. If the infant is acutely ill, vaccination should be postponed until recovery.