Diphtheria, Tetanus, Acellular Pertussis Vaccine (Dtpa)

7.1 The PBAC recommended a change to the circumstances under which dTpa is made available as a designated vaccine for the NIP to include vaccination of women during each pregnancy to reduce pertussis disease in infants (prior to being vaccinated) and in mothers on the basis of cost-effectiveness compared with no vaccination.PSD · Jul 2016

7.2 The PBAC noted the optimal timing of vaccination during pregnancy is an issue for further consideration in light of an emerging body of evidence supporting second trimester immunisation. Accordingly, the PBAC recommendation is for vaccination during each pregnancy, without the requested restriction to the third trimester. The PBAC considered the optimal timing of vaccination during pregnancy should be based on clinical evidence and informed by ATAGI.PSD · Jul 2016

6.26 The economic evaluation is a cost-utility analysis. The submission presented a decision tree model.PSD · Jul 2016

Table 5: Summary of model structure and rationale Time horizon The number of cases of pertussis occurring in one year is reported.  For infants there is a benefit of maternal vaccination for up to 7 months (after which the infant is covered by the primary DTPa doses).  For mothers dTpa is assumed to be effective for up to 5 years. The median follow-up in the clinical trial (APERT) was 22 months.PSD · Jul 2016

6.23 The submission described dTpa vaccination during the third trimester of pregnancy as superior in terms of comparative effectiveness in preventing pertussis in infants and mothers, and inferior in terms of comparative safety, over no vaccination. The ESC considered that these claims were appropriate and that the vaccine effectiveness for dTpa for prevention of pertussis in infants was likely to be high.PSD · Jul 2016

However, the submission did not provide clinical evidence on the effectiveness of dTpa in preventing pertussis in mothers. Although dTpa elicits a significant immunogenic response in mothers, there is no clear evidence supporting the correlation of immunogenicity outcomes and protection from pertussis. In the economic model it is assumed that the effectiveness of dTpa in the general population is directly applicable to pregnant women.PSD · Jul 2016

6.2 The PBAC noted and welcomed the input from individuals (132), health care professionals (4) and organisations (1) via the Consumer Comments facility on the PBS website. The comments described a range of benefits of including dTpa on the NIP for vaccination of pregnant women including avoiding infant deaths from pertussis, reduction in morbidity for adults, and improved access, information and certainty of funding associated with a national program …PSD · Jul 2016

6.3 The PBAC noted the advice received from Northern Rivers Vaccination Supporters Group which supported the request to list dTpa on the NIP for pregnant women to provide added protection to the infant in the first few weeks of life, until they are able to start their own vaccination schedule at six weeks old.PSD · Jul 2016