The Pfizer-BioNTech COVID-19 vaccine, also known as BNT162b2, 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 was developed by Pfizer, a pharmaceutical company, in collaboration with BioNTech, a biotechnology firm. It received emergency use authorization from health authorities around the world and has been shown to be effective in reducing the risk of severe illness, hospitalization, and death from COVID-19.