HPV and Vaccines
What is HPV? Human Papilloma Virus
- HPV is the name given to a very common group of viruses.
- There are many types of HPV, some of which are called “high risk” because they’re linked to the development of cancers, such as cervical cancer, anal cancer, genital cancers, and cancers of the head and neck.
- Other types can cause conditions like warts.
- Nearly all cervical cancers (99.7%) are caused by infection with a high-risk type of HPV. But only some of the anal and genital cancers, and cancers of the head and neck, are caused by HPV infection.
- The rest of these cancers are caused by other risk factors like smoking and drinking alcohol. HPV infections do not usually cause any symptoms, and most people will not know they’re infected.
What are the different types of HPV and what do they do?
- There are more than 100 different types of HPV, and around 40 that affect the genital area.
- HPV is very common and can be caught through any kind of sexual contact with another person who already has it.
- Most people will get an HPV infection at some point in their lives, and their bodies will get rid of it naturally without treatment.
- But some women infected with a high-risk type of HPV will not be able to clear it.
- Over time, this can cause abnormal tissue growth as well as other changes in the cells of their cervix, which can lead to cervical cancer if not treated.
How does the HPV vaccine work?
Two HPV vaccines are currently available worldwide:
- a bivalent vaccine, works against HPV types 16 and 18 (these two types cause 70% of cervical cancers in most of the world)
- a quadrivalent vaccine, works against HPV 16 and 18 as well as HPV 6 and 11 (6 and 11 are responsible for benign anogenital warts and recurrent respiratory papillomatosis, a disease
where recurrent growths occur in the airways, frequently on the vocal cords).
Neither vaccine contains a live virus; therefore, they don’t act by causing an infection.
Both vaccines are prophylactic (prevent HPV infections) and are most effective when administered prior to infection with HPV, which is acquired by most individuals shortly after sexual debut.
The vaccines are not therapeutic (cannot be used to treat existing HPV and HPV-related disease), nor do they have any effect on progression to disease (precancer and cancer) in persons who have HPV infection at the time of vaccination.
Who can have the HPV vaccine?
- The first dose of the HPV vaccine is routinely advised in girls aged 12 and 13. Both vaccines are administered in a schedule of currently 3 doses within 6 months. The dose for each vaccine is administered intramuscularly using 0.5 mL of liquid suspension.
- For the quadrivalent vaccine, the second dose is given 2 months after the first dose, and the last (third) is given 6 months after the first dose.
- For the bivalent vaccine, the second dose is administered 1 month after the first, and the third dose at 6 months after the initial dose.
- It’s important to complete all the doses of the vaccine to be fully protected.
- Re-starting is not necessary if the series is interrupted, but remaining doses should be administered as close to the recommended intervals as possible.
- Girls who missed their HPV vaccination can still be vaccinated up to their 25th birthday.
Why is the HPV vaccine given at such a young age?
- HPV infections can be spread by any skin-to-skin contact, and are usually found on the fingers, hands, mouth and genitals.
- This means the virus can be spread during any kind of sexual activity, including touching.
- The HPV vaccine works best if girls get it before they come into contact with HPV. In other words, before they become sexually active.
- So getting the vaccine when recommended will help protect them during their teenage years and beyond.
- Most unvaccinated people will be infected with some type of HPV at some time in their life.
- In most cases, the virus does not do any harm because their immune system clears the infection.
- But in some cases, the infection stays in the body for many years and then, for no apparent reason, it may start to cause damage.
Cervical screening (sometimes called a smear test) can detect these changes. The person can then be treated to stop cervical cancer developing. This will be started after the girls become sexually active and after the age of 26.