Costs of managing adverse reactions to hexavalent vaccines: Comparison of DT3aP-HBV-IPV/Hib and DT2aP-HBV-IPV-Hib in France and Spain.

Hexavalent vaccines DT3aP-HBV-IPV/Hib and DT2aP-HBV-IPV-Hib differ in composition and reactogenicity. Systematic reviews of randomized clinical trials of these vaccines showed that DT3aP-HBV-IPV/Hib causes fewer adverse reactions (ARs) than DT2aP-HBV-IPV-Hib. This study details a cost analysis evaluating the healthcare and societal economic impact of managing post-vaccination ARs when vaccinating infants with a dose of DT3aP-HBV-IPV/Hib versus DT2aP-HBV-IPV-Hib in France and Spain. A physician survey explored healthcare resource utilization (HCRU) when managing early childhood post-vaccination ARs in clinical practice; HCRU-associated costs were calculated from unit cost data. A parent/caregiver survey examined indirect costs when managing post-vaccination ARs in their child. A mathematical projection tool then estimated differences in cost between post-vaccination AR management with DT3aP-HBV-IPV/Hib versus DT2aP-HBV-IPV-Hib. Additionally, parent/caregiver emotional concerns over post-vaccination ARs were explored using Likert questions. In both countries, managing post-vaccination childhood ARs incurred an HCRU burden and parents/caregivers reported costs such as work absenteeism and out-of-pocket treatments. Vaccination with DT3aP-HBV-IPV/Hib over DT2aP-HBV-IPV-Hib reduced AR incidence, reducing direct medical costs in France and Spain by 10%, and indirect costs by 9% and 10%, respectively (projected cost uncertainty intervals not evaluated). Fever and local ARs incurred the greatest costs, with hospitalizations being the largest cost contributor. Parents/caregivers expressed emotional concern over post-vaccination childhood ARs (particularly rashes), with half seeking healthcare advice to manage ARs, which contribute to the overall economic burden. In summary, costs related to AR management were lower with DT3aP-HBV-IPV/Hib versus DT2aP-HBV-IPV-Hib. Results highlight the importance for decision- and policy-makers to consider reactogenicity during economic evaluations of vaccines.