OBJECTIVES: The Austrian population has achieved high immunity to Omicron through vaccination and natural infection. However, individuals aged ≥60 years and with pre-existing conditions are at increased risk for severe disease or COVID-19-related death. Additionally, long-term sequelae may occur in all infected individuals. Booster vaccinations (≥4^th dose) provide protection against infection and long-term sequelae. The aim of this BIA is to determine the monetary impact due to hypothetical increased booster vaccinations, expressed as a world with increased booster vaccinations compared to a world with an unchanged rate of booster vaccinations.

METHODS: A population-based assessment of Austrian COVID-19 cases, inpatient stays, deaths and vaccinations per age group (5-17Y, 18-59Y, ≥60Y) was performed for 2022. Age-specific infection- (IFR), hospitalization- (HR), and mortality-rates (MR) were stratified by vaccination-status using publicly available data. Effects of vaccine-induced-immunity were considered for individuals with no vaccine-induced-immunity (0/1^st dose), immunity after the first vaccination-series (2^nd dose ≤120d), expired immunity (2^nd/3^rd dose >120d, ≥4^th dose >180d) and immunity after basic immunization or booster (3^rd dose ≤120d, ≥4^th dose ≤180d). The BIA captures the benefit of 2.6 million additional booster vaccinations, which in a world with increased booster vaccinations leads to a larger at-risk-population with booster exposure and correspondingly lower IFR, HR, and MR.

RESULTS: Annual savings of 0 million € (m€) (1^st year) to 71.8 m€ (3^rd year) [total: 123.3 m€] could be reached over three years. Direct costs account for 0 m€ (1^st year) and 28.6 m€ (3^rd year) [total: 49.1 m€] of the total saving. Increased booster vaccinations reduce indirect costs between 0 m€ (1^st year) and 43.3 m€ (3^rd year) [total: 74.2 m€] annually. The total cost for boosters, borne by the health-care-system, range between 0 m€ (1^st year) and 49.1 m€ (3^rd year) [total: 96.8 m€] annually.

CONCLUSIONS: 1 € invested in boosters saves society 1.27 €.