Jung Yeon-Je/AFP via Getty Images The Delta Plus variant is the Delta variant with an extra mutation. It has reached nearly 30 countries. It's not yet clear whether Delta Plus is more transmissible than Delta. The fact that Delta remains dominant worldwide is a sign that Delta Plus won't overtake it soon. Insider Healthcare: The latest healthcare news & analysis Loading Email address By clicking ‘Sign up’, you agree to receive marketing emails from Insider as well as other partner offers and accept our Terms of Service and Privacy Policy. As the Delta variant tears across the globe, scientists are keeping a close eye on its relative: Delta Plus.