HPV Vaccines

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What is HPV?

HPV is short for human papilloma virus. HPVs are a group of more than 150 related viruses. Each HPV virus in the group is given a number, which is called an HPV type. HPVs are called papilloma viruses because some of the HPV types cause warts or papillomas, which are non-cancerous tumors. But some types of HPV are known for causing cancer, especially of the cervix (the base of the womb at the top of the vagina).

The papilloma viruses are attracted to and are able to live only in certain cells in the body called squamous epithelial cells. These cells are found on the surface of the skin and on moist surfaces (called mucosal surfaces) like:

    • the vagina, anus, cervix, vulva (around the outside of the vagina)

    • the inner foreskin and urethra of the penis

    • inner nose, mouth, throat

    • trachea (the main breathing tube), bronchi (smaller breathing tubes branching off the trachea)

    • the inner eyelids

Of the more than 150 known strains, about 3 out of 4 (75%) HPV types cause warts on the skin – often on the arms, chest, hands, and feet. These are common warts; they are not the genital type of wart.

The other 25% of the HPV types are considered mucosal types of HPV. “Mucosal” refers to the body’s mucous membranes, or the moist surface layers that line organs and cavities of the body that open to the outside. For example, the mouth, vagina, and anus have this moist mucosal layer. The mucosal HPV types are also called the genital (or anogenital) type HPVs because they often affect the anal and genital area.


Last Medical Review: 04/09/2014
Last Revised: 12/12/2014