Human papillomavirus (HPV) is a group of more than 100 different types of viruses. More than 40 types of HPV are transmitted through sexual intercourse, genital skin-to-skin contact and oral sex. These types can infect the genital areas of both men and women, including the penis, anus, vulva, vagina and cervix, as well as the oral cavity and throat (the oropharynx).
It is estimated that about 75% of sexually active men and women will have at least 1 HPV infection in their lifetime. Young women 20-24 years old generally have the highest rates of cancer-causing HPV infection (24%). Infection rates decrease as women get older because most develop immunity against the virus.
Sexually transmitted HPV are either high-risk or low-risk.
High-risk HPV
Infection with high-risk HPV can cause the cells in a woman’s cervix to change or become abnormal. These precancerous changes can lead to cervical cancer. HPV 16 and 18 are the most common high-risk types and are responsible for 70% of cervical cancers.
Infection with high-risk HPV, especially HPV 16, is also linked to cancers of the penis, anus, vulva, vagina, as well as the oral cavity and throat. Not all cases of these rare cancers are linked to having an HPV infection.
Low-risk HPV
Infection with low-risk HPV doesn’t cause precancerous changes in the cervix and doesn’t increase a woman’s risk of cervical cancer. But low-risk types of HPV can cause genital warts. The two low-risk types of HPV that are responsible for 90% of genital warts are HPV 6 and 11.
HPV 11 can also cause recurrent laryngeal papillomatosis (tumours that grow inside the larynx, vocal cords or respiratory tract). This is a rare condition that can affect children, adolescents, and young adults.
Symptoms of HPV infection
Most people will never know they have been infected because HPV usually doesn’t cause any symptoms (unless you are infected with the type that causes genital warts). This means you can get HPV and pass it along without ever knowing it. While an HPV infection can’t be treated, what it causes can.
- Precancerous cervical changes can develop if there is a persistent or continuous high-risk HPV infection. Precancerous cervical changes and cervical cancer can be treated.
- Genital warts caused by low-risk types of HPV can appear weeks or months after skin-to-skin sexual contact with an infected person. There are treatments for genital warts
HPV and cervical cancer
Most men and women who are sexually active will have an HPV infection at some point over their lifetime. In most cases, high-risk type HPV infections go away on their own within a few months. For most women, the virus will no longer be detected after 2 years. Sometimes the HPV infection does not go away. This can lead to changes in the cells of the cervix. These changes can develop into cervical cancer if they are not detected early and treated.
Preventing HPV infection
The only sure way to prevent HPV infection is to completely avoid any genital contact with another individual. If you are sexually active, you can reduce your risk by:
- having as few sexual partners as possible
- being in a monogamous relationship with someone who hasn’t had a lot of sexual partners
- using condoms
Using a condom can reduce HPV infection if it is put on before skin-to-skin sexual contact. However, areas not covered by a condom still allow some skin-to-skin contact during sexual activity. So using them will reduce, but not eliminate, the risk of HPV infection.
Two vaccines that protect against HPV 16 and 18 infections are available in Canada.
HPV vaccines
There are two vaccines to protect against HPV infection in Canada – Gardasil and Cervarix. HPV vaccines do not treat HPV infections you already have or treat diseases or cancers related to HPV.
Gardasil
Gardasil protects males and females against HPV types 6, 11, 16 and 18. (Because this protects against 4 types of infection, it is called a quadrivalent vaccine.)
Cervarix
Cervarix protects females against HPV types 16 and 18. (Because this protects against 2 types of infection, it is called a bivalent vaccine.)
Canadian Cancer Society recommendation on HPV vaccination
HPV vaccines should be available and affordable to Canadians.
Girls and women between the ages of 9 and 45 should be vaccinated against HPV to help reduce their risk of HPV-related cancers. These include cervical, vaginal, vulvar and anal cancers and precancerous conditions associated with these cancers. HPV vaccination should be used along with, not instead of, cervical cancer screening.
Boys and young men between the ages of 9 and 26 should be vaccinated against HPV to help reduce their risk of HPV-related cancers such as anal cancer.
The vaccines work the best when they are given before a person becomes sexually active.
Talk to your doctor about which vaccine is right for you and when you should have it.
The HPV vaccines have been approved and recommended by Health Canada and the National Advisory Committee on Immunization (NACI). Health Canada approves vaccines based on their effectiveness and safety, while NACI provides recommendations for how the vaccines should best be used to prevent disease. The most recent NACI recommendations were made in 2012.
Vaccination of girls and women
NACI recommends both vaccines for the prevention of cervical cancer and precancerous cervical changes in:
- Females 9 to 26 years of age. The vaccines are most effective when given to females before they are sexually active (which includes sexual intercourse, genital skin-to-skin contact and oral sex).
- Females between 14 and 26 years of age who have been sexually active, have had previous abnormal Pap tests, including cervical cancer, or have had genital warts. The vaccine may protect them from HPV types they haven’t been exposed to.
- Females over 26 years of age. Gardasil is effective in females between 27 and 45 years of age. The effectiveness of Cervarix has not been tested in this age group, but there is some evidence from immune responses in younger women to suggest that the vaccine will have similar effectiveness in older women.
Only Gardasil is approved for girls and women aged 9 to 45 to prevent vaginal and vulvar cancer, their precancers and anogenital warts. Gardasil is also the only vaccine approved for girls and women aged 9 to 26 to prevent anal cancer and its precancer.
Importance of cervical cancer screening
If you’re sexually active, you should start having regular Pap tests by the time you’re 21 – even if you’ve had the HPV vaccine. HPV vaccines prevent infection from HPV types associated with only 70% of cervical cancers. So, about 30% of cervical cancers will not be prevented by the vaccines.
HPV vaccines should be viewed as a complement to cervical cancer screening – they do not replace it.
Vaccination of boys and men
Only Gardasil is approved by Health Canada for boys and young men to prevent anal cancer, its precancer, and anogenital warts. The vaccine is most effective when given to males before they become sexually active.
NACI recommends this vaccine for:
- males between 9 and 26 years of age
- males 9 years of age and older who have sex with males
There is some evidence that Gardasil can also prevent penile cancer and its precancer, although it is not currently approved for this use.
Research is also being done to see if vaccinating boys before they become sexually active can prevent them from passing on HPV to females. In turn, this could help reduce cervical cancer risk in women.
Dosing, safety and vaccination programs
The vaccines are most effective when given in 3 doses over a 6-month period. If all 3 doses are not given, or if they are not given at the right time, you may not get the full benefit of the vaccine. Research is being done to see if fewer doses can be given to get the same level of protection. At this time, NACI is not recommending a 2-dose schedule of either HPV vaccine.
Vaccine safety
Current evidence tells us that the vaccines are safe and most of the side effects that occur are not serious. The safety of both HPV vaccines is being followed in Canada and other countries on an ongoing basis. The vaccines are not recommended for:
- anyone under 9 years of age
- pregnant women
Provincial and territorial vaccination programs
All provinces and territories have voluntary, school-based HPV vaccination programs for girls 9 to 13 years of age (grades 4 to 8). In spring 2013, Prince Edward Island became the first province to provide announce its intent to provide school-based HPV vaccination for boys.
Length of protection
How long the HPV vaccines provide protection for is not known. Information so far shows that protection is up to 5 years for Gardasil and up to 6.4 years with Cervarix in women not infected with HPV at the time of vaccination. Information from longer follow-up of both vaccines will provide answers on:
- long-term effectiveness
- how long protection lasts
- whether booster doses will be needed for continued protection
HPV vaccines and other cancers
More research is needed to know if HPV vaccines will also prevent other cancers associated with HPV, such as cancer of the mouth and throat.
Some research shows that both vaccines may also provide protection against other high-risk HPV types, which are similar to HPV 16 and 18. But more research is needed.
The HPV vaccines do not protect against breast, ovarian, prostate and other reproductive cancers because these cancers are not caused by HPV.
Vaccine research and surveillance
HPV vaccines may be very effective in reducing the number of women who get cervical cancer. However, ongoing research and monitoring is needed to find out:
- how many people are getting vaccinated
- the impact the vaccine has on reducing the number of people with HPV infection
- the impact the vaccine has on reducing the incidence of cervical cancer and other HPV-related cancers and precancerous conditions
- the long-term safety of the vaccines and how long and how well they will provide protection
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