5 Diphtheria

5.5 Recommended immunisation schedule

5.5.1 Usual childhood schedule

A primary course of diphtheria vaccine is given as DTaP-IPV-HepB/Hib (Infanrix-hexa) at ages 6 weeks, 3 months and 5 months, followed by a dose of DTaP-IPV (Infanrix-IPV) at age 4 years. A booster is given at age 11 years (school year 7), which includes a pertussis component given as the vaccine Tdap (Boostrix).

If a course of immunisation is late or interrupted for any reason, it may be resumed without repeating prior doses (see Appendix 2).

Dose intervals between Td and Tdap

No minimum interval between Td and Tdap is required,19–21 unless Tdap is being given as part of a primary immunisation course.

Alternatives to pertussis-containing vaccines

Some parents or guardians may ask about alternatives to pertussis-containing vaccines. The recommended and funded vaccines for children are those described above. There are no diphtheria-only or tetanus-only vaccines available. The Td vaccine contains half the amount of tetanus toxoid and one-fifteenth the amount of diphtheria toxoid compared to the DTaP-containing vaccines. Td was not clinically designed or tested for use to provide the primary vaccine course in children and it is not registered for use in children aged under 5 years. Although there are no safety concerns relating to administration of the vaccine, there is no data on the use of this vaccine for a primary course in children and it is not recommended.

5.5.2 Catch-ups for individuals aged 10 years and olderTop

For previously unimmunised individuals aged 10 years and older, a primary immunisation course consists of three doses of a diphtheria toxoid-containing vaccine at intervals of not less than four weeks (see Appendix 2). A booster dose is recommended at least six months after the third dose. Children aged under 18 years may receive Tdap (funded from age 7 to under 18 years); adults aged 18 years and older may receive Td (funded) or Tdap (unfunded). Although Tdap and Td are not approved for use (registered) as a primary course, there are expected to be no safety concerns.

Dose intervals between Td and Tdap

No minimum interval between Td and Tdap is required,19–21 unless Tdap is being given as part of a primary immunisation course.

5.5.3 Booster doses for adultsTop

Studies overseas show that many adults lack protective levels of the antibody, and this has led to concern about waning immunity and recommendations for booster doses beyond childhood (see also section 5.3.2). Most authorities recommend maintaining diphtheria immunity by periodic reinforcement using Td.3 A single booster dose of Tdap induces seroprotective levels of antibodies to diphtheria and tetanus in virtually all children and adolescents, and in a high proportion of adults and elderly individuals at approximately one month post‐vaccination, irrespective of their vaccination history.22

In New Zealand, following the dose of Tdap at age 11 years, booster doses of Td are recommended (the vaccine is funded, but not the administration) at ages 45 and 65 years. These age-specific recommendations may facilitate the linkage of adult immunisation to the delivery of other preventive health measures.

Tdap boosters are also funded for pregnant women, from 28 to 38 weeks’ gestation (see section 14.5).

Booster doses before travel

If someone is travelling to an area endemic for diphtheria, or there is another reason to ensure immunity, a booster dose is recommended (but not funded) if it is more than 10 years since the last dose. For website sources on travel vaccines, see Appendix 9.

5.5.4 (Re-)vaccinationTop

Diphtheria-containing vaccines are funded for (re-)vaccination of eligible patients, as follows.

DTaP-IPV-HepB/Hib (Infanrix-hexa; for children aged under 10 years), DTaP-IPV (Infanrix-IPV) and Tdap (Boostrix) are funded for patients:

Td (ADT Booster) is funded for patients following immunosuppression.

See also sections 4.2 and 4.3.