The novel corona virus causing severe acute respiratory symptoms appeared in China at the end of year 2019 and soon spread globally resulting in Pandemic. The susceptibility to novel corona virus infection and severity of symptoms in an individual is an outcome of immune system of the host. The Human leucocyte Antigen (HLA) of an individual is responsible for regulation of immune system. Thus, genetic variability of the HLA can affect the individual's response to Novel corona virus infection in terms of susceptibility and severity. The memory B cells which persist in the body after initial infection protect by faster response to repeat infection by the virus. However viral mutations prevent recognition by memory B cells and therefore repeat infection by virus leads to slow immune response as immunity to the mutated virus is not present.