The Potential Clinical and Economic Impact of a Combination COVID-19 and Influenza Vaccine (mRNA-1083) in Canada

Aims: COVID-19 and influenza continue to impose a substantial burden on the Canadian healthcare system, particularly among adults aged greater than 65 years. This study compared the clinical and economic outcomes of a Stand-alone vaccination strategy with separate influenza and COVID-19 vaccines versus a Combination strategy incorporating mRNA-1083, an investigational vaccine targeting both infections. Methods: The study adopted the public healthcare payer perspective and adapted a previously published static model to predict COVID-19 and influenza infections across a one-year time horizon. Relative vaccine effectiveness (rVE) for mRNA-1083 against COVID-19 compared with the stand-alone vaccine (SPIKEVAX) was based on the pivotal clinical trial of mRNA-1083s COVID-19 component (mRNA-1283). For influenza, no incremental VE was assumed versus the adjuvanted stand-alone vaccine (FLUAD). Infections were modeled independently. Clinical outcomes included symptomatic infections, hospitalizations, and deaths. The economically justifiable price (EJP) was calculated at the willingness-to-pay (WTP) threshold of $50,000 per quality-adjusted life-year (QALY) gained. mRNA-1083 uptake was assumed to yield absolute increases in COVID-19 and influenza coverage by 10% and 3%, respectively. Results: Compared with the Stand-alone strategy, the Combination strategy was projected to reduce the number of COVID-19-related symptomatic infections, hospitalizations, and deaths (n=71,074; 5,008; 935, respectively), and corresponding influenza outcomes (n=3,985; 362; 69, respectively). The use of mRNA-1083 within the Combination strategy generated a cost-savings of $90,440,471 in vaccine administration fees and an EJP of $304 per dose. Results were sensitive to rVE, coverage, administration fees, mortality and incidence. Limitations: mRNA-1083s rVE is being evaluated in clinical trials and the impact of mRNA-1083 on vaccine coverage and administration fees is uncertain. Conclusions: mRNA-1083 may reduce the burden of COVID-19 and influenza in adults aged greater than 65 years in Canada, while offering good economic value because it has the potential to increase coverage and VE while reducing administration fees.