The Moderna vaccine, officially known as mRNA-1273, is a vaccine developed to protect against the COVID-19 virus. It uses messenger RNA (mRNA) technology to instruct cells in the body to produce a harmless piece of the virus's spike protein. This prompts the immune system to recognize and fight the virus if exposed in the future. The vaccine is administered in two doses, typically given four weeks apart. Clinical trials have shown that the Moderna vaccine is effective in reducing the risk of severe illness, hospitalization, and death caused by COVID-19. It has received emergency use authorization in many countries worldwide.