This is a citation of an outside article. Gravyday is not responsible for its content. Original URL below. Johnson & Johnson’s one-shot COVID-19 vaccine is effective against severe disease The shot doesn’t work as well at preventing people from getting moderately sick A single-shot coronavirus vaccine made by Johnson & Johnson is 85 percent effective at preventing severe disease and death, even against new variants of the virus, the company announced in its interim analysis January 29.(more)