Economic evaluations of inactivated COVID-19 vaccines in six Western Pacific and South East Asian countries and regions: A modeling study

OBJECTIVE: The present study aimed to document the economic profiles of inactivated COVID-19 vaccines in Hong Kong SAR, Indonesia, mainland China, Philippines, Singapore, and Thailand, the evidence on which is currently absent. METHODS: Decision tree models were developed to assess the cost-effectiveness of two doses of inactivated COVID-19 vaccines at a population vaccination rate of 50% in the base case, which was an estimate of feasible vaccination coverage according to previous studies. Epidemiological, mortality, cost, and health state utility information were sourced from the literature. Vaccine efficacy against COVID-19 cases by severity were estimated using meta-analyses of publicly accessible phase 3 trial results of inactivated vaccines. The health outcomes were quantified as quality-adjusted life years (QALYs) and compared across the vaccination and no vaccination strategies. In scenario analyses, incidence and vaccination rates were changed semi-continuously over spectrums, the results of which were presented as contour lines informing the efficiency frontiers of vaccination strategies. One-way and probabilistic sensitivity analyses were also conducted. RESULTS: The vaccination strategy was dominant in all jurisdictions in the base case by producing 105.18, 98.15, 99.70, 60.48, 112.00, and 103.47 QALYs while saving US$40.26 million, US$5.26 million, US$7.60 million, US$5.91 million, US$21.33 million, and US$7.18 million in Hong Kong SAR, Indonesia, mainland China, Philippines, Singapore, and Thailand per every 100,000 vaccinated individuals, respectively. Results were robust in alternative model specifications. CONCLUSIONS: Inactivated COVID-19 vaccines may be cost-saving options in Hong Kong SAR, Indonesia, mainland China, Philippines, Singapore, and Thailand. Mass vaccination programs using inactivated COVID-19 vaccines should be considered in these jurisdictions.