Evaluation of vaccine allergy safety track program to assess potential COVID-19 vaccine allergy: a cost-effectiveness analysis.

Background: Concerns about new COVID-19 vaccines played a key role in vaccine hesitancy and hampered population uptake. Hong Kong initiated a Vaccine Allergy Safety Track (VAS-Track) program to assess potential COVID-19 vaccine-associated allergies. A 'Hub-and-Spoke' model of predominately non-specialists supported by the allergist hub was established to meet overwhelming demand despite limited specialists.

Objective: To assess the cost-effectiveness of VAS-Track as a pre- and post-vaccination assessment service for individuals potentially at high risk of COVID-19 vaccine-related allergy.

Methods: An individual-level decision-analytical model was constructed using data from VAS-Track participants supplemented by published estimates. Analyses were from a health service provider perspective over 12 months. We calculated the incremental cost-effectiveness ratio (ICER) to estimate the cost per quality-adjusted life years (QALYs) gained. Willingness-to-pay threshold was based on local GDP per capita (US$ 49,590). Sensitivity analyses examined robustness of findings.

Results: Cost-effectiveness varied widely across age groups. VAS-Track was cost-saving for older adults (dominant strategy for age ≥ 50) compared with standard practice across a range of sensitivity analyses. VAS-Track was not cost-effective for younger groups (age 18-49: ICER: US$ 410,914/QALY for pre-vaccination and US$ 213,786/QALY for post-vaccination assessments). Infection rate, cost of treating severe infection, and vaccination rate were most influential on cost-effectiveness estimates.

Conclusion: VAS-Track was cost-effective both as a pre- and post-vaccination assessment service for adults over 50. The 'Hub-and-Spoke' model using non-specialists with limited allergy specialist resources to provide vaccine allergy assessment services would provide high economic value compared with usual care for adults aged 50 and over.