Efficacy Thresholds for Cost-Saving Antiviral SARS-CoV-2 Treatment Strategies: A Modelling Study

Background: In 2023 SARS-CoV-2 was declared endemic, yet hospital admissions persist within high-risk and moderate-risk populations. Antiviral treatments, currently only available for high-risk individuals, play an important role in preventing severe disease and hospitalisation within this subpopulation. Here, we further explore the public health and economic benefits of extending target populations for treatment, and assess efficacy thresholds for a treatment strategy to be cost-saving.Methods: We adapted an individual-based transmission model of SARS-CoV-2 to estimate hospitalisations and overall costs for three risk groups for a full range of treatment efficacies and coverages. We further calculated efficacy thresholds for strategies to be cost-saving. A global sensitivity analysis was conducted to test the sensitivity of all outcomes for a wide range of treatment properties, emerging variant properties, and vaccination coverages.Findings: In a high vaccination coverage setting, we found that a high efficacy treatment given to those at high-risk could reduce hospitalisations by up to 40%. When expanding treatment coverage to the moderate-risk group, an additional 50% of hospitalisations could be averted. Targeting both high-risk and moderate-risk groups was found to be cost-saving for a treatment efficacy greater than ~40%. This threshold was found to be highly sensitive to treatment costs, but relatively unsensitive to vaccination coverage and emerging variant properties.Interpretation: For a sufficiently efficacious antiviral treatment, expanding the target population to include both high-risk and moderate-risk groups should be considered. Equitable treatment costs are found crucial in achieving the best possible public health and health economic outcomes.Funding: Botnar Research Centre for Child Health (DZX2165 to MAP), the Swiss National Science Foundation Professorship of MAP (P00P3_203450) and Swiss National Science Foundation NFP 78 Covid-19 2020 (4079P0_198428 to MAP).Declaration of Interest: The authors declare no competing interests.