Microorganisms lives with us in our environment, touching infectious material on the surfaces by hand-mouth which causes infectious diseases and some of these diseases are rapidly spreading from person to person . These days the world facing COVID-19 pandemic disease . This article concerned with existence of results and stability analysis for a nabla discrete ABC-fractional order COVID-19 . The nabla discrete ABC-fractional operator as more general and applicable in modeling of dynamical problems due to its non-singular kernel . For the existence and uniqueness theorems and Hyers-Ulam stability, we need to suppose some conditions which will play important role in the proof of our main results . At the end, an expressive example is given to provide an application for the nabla discrete ABC-fractional order COVID-19 model.