Vaccine For HPV and Cervical Cancer?

Gardasil, the HPV vaccine...what is it all about? I am a pharmacist and get this question quite a bit.

So here is the scoop...   It was really made to be the cervical cancer vaccine because 99% of cervical cancer is linked to HPV.    The human papillomavirus (HPV) is a virus that has a lot of different strains (i.e. HPV-1, HPV-2, etc.). Some HPV strains cause common warts on feet, hands, etc.   Then there are sexually transmitted HPV strains that cause genital and anal warts. Other STD HPV strains have been linked to different cancers (penile, rectal). Then even other STD HPV strains (there are a bunch!) have been linked to cancer of the cervix (these are called high risk strains).  

As I mentioned before, studies show that 99% of women with cervical cancer also have HPV.   However, not everyone with high risk HPV will get cervical cancer. Most cases of HPV (all strains) are cleared naturally by the body within 2 years.   

Sometimes the high risk HPV will stick around longer -for these women their risk for cervical cancer goes up.   However, they still may not get cervical cancer because high risk HPV plus some other things (which have not been figured out yet) together cause cervical cancer.    

It is like an equation: high risk HPV + X + Y = cervical cancer.  

So, the idea is if we can vaccinate for high risk HPV -we can take the HPV out of the equation and hopefully decrease the risk of getting cancer of the cervix.     In the States we now have Gardisil -the HPV vaccine that covers:

1.     Two high risk HPV strains that are responsible for 70% of all cervical cancer cases and   

2.     Two HPV strains that cause 90% of genital wart cases.  

The vaccine is relatively new -it was released in the States in 2006. Currently it is approved girls and women 9 to 26 years old and is given at a 3 shot series (given at 0, 2 month and 6 months).   Even with the vaccine, there is a risk to get high risk HPV because 1) it does not necessarily protect 100% and 2) it does not cover 30% of the strains of high risk HPV that can lead to cancer of the cervix.  

Common side effects include pain and swelling at injection site, headache, fever, fainting. More serious side effects include seizures, Guillain-Barre syndrome, severe allergic reaction and 17 deaths (although they were ruled as not related).  

So...does it work?  Well, for now the studies show that it works very well to prevent genital warts and abnormal pap smears. But because it is so new, there are a few issues to be worked out...

1.     Studies show that the 3 part vaccine will protect for at least 5 years -it is not known yet if the girls/women will need a booster shot later

2.     It is assumed that because the vaccine decreased abnormal pap smears that it will lessen cases of cervical cancer too -however because cancer of the cervix usually takes at least 10 years to show up after being infected with high risk HPV and it is still relatively early in the test girls/women, it is not yet proven.