In most cases, doctors cannot attack the cause of the disease itself, because most drugs able to kill or damage a virus also damage healthy cells. Researchers have found other potential antiviral drugs, including interferons. But these drugs must undergo further testing before their safety and effectiveness are known. Until then, the best way to deal with viruses is immunization before a virus disease strikes. Immunization with vaccines causes the immune system to produce antibodies that will resist a virus when it enters the body.
Doctors use vaccines in order to prevent such virus diseases as influenza, measles, and polio.
A few viruses are called slow viruses because they reproduce more slowly than the others. Other viruses, such as the herpesviruses, can remain dormant in cells for years and then become reactivated and cause sporadic outbreaks of symptoms. Still other viruses including HIV, the virus that causes AIDS, can cause prolonged, persistent infections in which the virus multiplies continuously. Some viruses have been linked to human cancer. For example, hepatitis B virus is linked to hepatoma, a type of liver cancer.