Notably, the vaccinated mice displayed a lower concentration of most cytokines and chemokines after infection (Fig. 5f), including IL-5, IL-22, IP-10 and MCP-3 (Fig. 5f–j), suggesting that the combined mRNA vaccine effectively reduces proinflammatory cytokines and confers protective efficacy against influenza virus and SARS-CoV-2 coinfection. Here, CCL7 is linked to infection.