I have ewdited my above post to read "DTaP-IPV" - the Boostrix vaccine (which covers for diptheria, tetanus, and pertussis) is only licensed for used in children 10 and over. The Infanrix-IPV vaccine (which is a DTaP-IPV vaccine, or diptheria, tetanus, pertussis, and polio) is licensed for 6 months to 8 years of age.

For a 14 month old, I am unsure. There is a chance 2 doses would be sufficient, but I am guessing that that chance is less than for an older child.