The Johnson & Johnson vaccine, officially known as the Janssen COVID-19 vaccine, is a single-dose vaccine designed to protect against the COVID-19 virus. It uses a modified adenovirus to deliver genetic material that instructs cells to produce a harmless piece of the virus, prompting an immune response. This vaccine received emergency use authorization from the U.S. Food and Drug Administration (FDA) in February 2021. It is notable for its convenience, as it requires only one shot, making it easier to distribute and administer compared to two-dose vaccines like those from Pfizer-BioNTech and Moderna.