The clinical and economic value of enhanced influenza vaccines for the elderly in Argentina

Background

Enhanced influenza vaccines are the best option for the elderly. In 2021, Argentina introduced the MF59-adjuvanted inactivated influenza vaccine (aIIV) for individuals aged 65 years. and above, in the national immunization program. High dose inactivated influenza vaccine (HD-IIV) is also currently registered. This study evaluates the clinical and economic outcomes of these noted enhanced influenza vaccines for the elderly in Argentina.

Methods

Using a static decision-tree model and adopting the payer's perspective during an average influenza season, the analysis incorporated influenza epidemiological data from pre-pandemic Argentinian seasons (2014–2019), strain distribution, vaccination uptake, influenza-related costs and Quality-Adjusted Life-Years (QALYs) gained. Results include two relative vaccine effectiveness (rVE) scenarios from two published meta-analyses, due to reported rVE variability, although without statistical significance expected between enhanced vaccines. Vaccination acquisition costs were obtained from aIIV manufacturer, while HD-IIV costs were estimated using local (Argentinian private sector) and international public sector data (Europe). This assessment considered one GDP per-capita (US$13,696) as a cost-effectiveness threshold and included multiple sensitivity analysis.

Results

With an expected lower vaccine cost and non-significant higher rVE for aIIV vs HD-IIV (3.2 %), aIIV generated 41.4 QALYs gained and US$8.7 M savings to the Argentinean public health system. In this scenario aIIV resulted as a dominant strategy over HD-IIV. On a second scenario, where HD-IIV has a non-significant higher rVE compared to aIIV (15.9 % and 13.9 % for HD-IIV and aIIV, respectively, both vs standard-dose IIV), HD-IIV would only result cost-effective compared to aIIV if its public price is up to 25 % the incremental cost in relation to the standard-dose IIV acquisition price.

Conclusions

In Argentina, the use of enhanced influenza vaccines in the elderly can increase vaccine effectiveness, reduce mortality and disease-related costs. Based on comparable effectiveness, the economic advantage of aIIV over HD-IIV confirms the current vaccination strategy employing aIIV in Argentina.