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What is a virus?

A virus is an infectious agent that contains genetic material, either RNA or DNA, with a protein coat around it. Viruses are microscopic, and to multiply, they must invade a host. The host can be a human, plant, animal, or bacteria.

When a virus enters a host cell, it hijacks the cell and begins producing its own genetic material and proteins. It then uses the cellular machinery of the host cell to make copies of itself.

Some viruses, when they infect their host, can cause disease. For example, the influenza virus can cause the flu.

Viruses may also affect different hosts in different ways. This is why a virus that may be dangerous to humans does not affect dogs and cats.  

There are also various qualities of viruses, such as:

  • their shape and size
  • their type of nucleic acid
  • the presence of a protective lipid envelope derived from the host cell

How do viruses impact healthcare?

While a few “friendly” viruses protect the body from other types of infection, viruses most often cause infection and potential disease.

Some diseases that are due to viruses include:

  • mononucleosis

  • smallpox

  • COVID-19

  • measles

  • the common cold

  • rubellavaria

  • flu

  • chickenpox

  • mumps

  • Ebola

  • rabies

  • polio

  • herpes simplex virus (HSV)

  • HIV

  • dengue fever

A significant concern within healthcare is the effect of viruses as they mutate. As viruses reproduce, there may be genetic changes that naturally occur due to “copying errors.” This can cause different strains of a virus, and in some cases, these variants are more dangerous than the initial virus. For example, the different strains can be more transmissible or more easily evade the immune system and existing vaccines and treatments.