The Pfizer-BioNTech COVID-19 Vaccine is an mRNA vaccine designed to protect against the COVID-19 virus. 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, which triggers an immune response. This helps the body recognize and fight the virus if exposed in the future. The vaccine is administered in two doses, typically three weeks apart. Clinical trials have shown it to be effective in reducing the risk of severe illness, hospitalization, and death caused by COVID-19. It has received emergency use authorization from health authorities worldwide.