Effectiveness of An Influenza/COVID-19 Vaccine (mCombriax [mRNA-1083]) in Adults ≥ 65 Years

This Phase 4 randomized, active-comparator, pragmatic trial is designed to evaluate the effectiveness of a seasonal variant-containing formulation of mCombriax® (mRNA-1083) compared with same-day co-administration of authorized standalone enhanced influenza and COVID-19 vaccines in adults aged ≥65 years. The trial is designed to be conducted over two consecutive respiratory virus seasons to account for potential seasonal variation in virus circulation, vaccine composition, and effectiveness. The primary objective is to evaluate the comparative vaccine effectiveness (cVE) of the combination vaccine with respect to clinically relevant outcomes, including severe influenza and COVID-19. Demonstration of non-inferior protection in real-world setting, in combination with the potential programmatic advantages of a single-dose strategy, may support policy recommendations, reimbursement decisions, and broader implementation of combined seasonal respiratory vaccination strategies.

Inclusion criteria

• Age ≥65 years at the time of vaccination
• Self-reported ability to understand written and spoken English or Danish (Denmark only) or Spanish or Galician (Spain only)
• Informed consent form has been signed and dated

Exclusion criteria

• There are no specific exclusion criteria for this study