Host cells will then reproduce cells still carrying the viral genetic information. Then, viruses might come back years, or even decades later, reactivating the viral replication when the immune system degrades. This prudent strategy where viruses turn into a latent enemy within the host is quite an effective strategy against the enemy, whether in the military or the human body. The scientific community is very familiar with five types of viruses that are able to "hibernate" and reactivate given suitable conditions:Herpes simplex virus, which causes blisters in the mouth and genital herpes. It is extremely common;