The Moderna COVID-19 vaccine is an mRNA vaccine designed to protect against the SARS-CoV-2 virus, which causes COVID-19. It works by using a small piece of the virus's genetic material to instruct cells in the body to produce a harmless spike protein. This triggers an immune response, helping the body recognize and fight the virus if exposed in the future. Approved for emergency use in many countries, the vaccine is administered in two doses, typically spaced four weeks apart. Clinical trials have shown it to be effective in reducing the risk of severe illness, hospitalization, and death from COVID-19.