How Does Epstein-Barr Work? Stage one of Epstein-Barr begins when the virus enters the body. Stage two begins when the immune system is weakened and you contract mononucleosis and your immune system goes to war with the virus. It is the invader vs. the white blood cells. But many people never even know they had mono. That’s why Epstein-Barr can live in your body for years, even decades, without being recognized before symptoms start to surface. You’re not alone and you deserve answers. Comment ‘