We mistakenly gave Kinrix (DTaP-IPV) to a child age 3 years 10 months. We later realized that he had a prior history of receiving 4 doses of DTaP and IPV. Can the dose of Kinrix count as his 4-year-old booster?

Use of either Kinrix (GSK) or Quadracel (Sanofi) in a child younger than age 4 years is off-label and is not recommended. You should take measures to prevent this error in the future. The minimum age for the fifth dose of the DTaP series is 4 years, and the minimum age for the final dose of IPV is also 4 years, so this dose of Kinrix is not valid. Both the DTaP and IPV will need to be repeated after the child’s fourth birthday.

For detailed information, see CDC’s useful table “Recommended and Minimum Ages and Intervals Between Doses of Routinely Recommended Vaccines” at www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/A/age-interval-table.pdf.