Last week on Being Brazen, a discussion started about the safety of the HPV vaccine (i.e. the vaccine that can prevent cervical cancer).
I asked the Doc aka tha Gynae aka the Baby Deliverer to write us an article explaining it all.
Preventing Cervical Cancer
Cervical cancer is the second leading cause of death from cancer in women worldwide.
What is unique about cervical cancer unlike other cancers is that we know what causes it. High-risk human papillomavirus (HPV) has been shown to cause cervical cancer. Because we know what causes it, it has been possible to develop a vaccine that has been proven to significantly reduce the individual’s chance of developing cervical cancer.
Currently, the targets for HPV vaccination are girls and young women aged 11–26 years before sexual debut. However, there is anecdotal evidence that even women who have already had intercourse and older women may benefit from the HPV vaccine.
HPV is a widely found DNA virus that is transmitted by skin to skin contact (shedding of viral cells from the infected host’s skin). Up to 70% of sexually active women will be infected with HPV at some point in their lifetime.
While there are over 100 different sub-types of HPV, there are 4 types that we need to know about:
HPV strains 16 & 18 cause about 75% of cervical cancer (as well as vulval & penile cancer);
HPV strains 6 & 11 cause about 90% of genital warts. Genital warts are usually flesh-colored growths that can be raised or flat, small or large, and alone or in cauliflower-like clusters.
HPV infects both women & men.
You can get HPV through any kind of genital contact with someone who has HPV (not just penetrative sex) i.e. through what middle aged folks call “heavy petting” ie hands touching genitals.
Many people who have HPV have no symptoms and that means that you can get the virus or pass it on to your partner without knowing it.
After the cervix is infected with HPV, infection may cause mild abnormalities which usually clear spontaneously.
But in some cases the HPV infection persists. The persistence of high-risk HPV (HPV strains 16 & 18) is a key factor in the ultimate development of cervical cancer.
The progressive development of cellular changes from HPV infection to cervical cancer generally takes 10–20 years, although, in very few cases, it may only take 1–2 years.
While persistence of high-risk HPV is a key factor in the development of cervical cancer, most HPV infections (80%) resolve spontaneously.
Unfortunately, we are unable to determine which women will develop HPV persistence (with the exception of those women who are immune-compromised e.g. HIV+, who we do know have an increased risk of HPV persistence).
Can HPV be treated?
There is no specific treatment for HPV infection and HPV infection cannot be eradicated.
Medical mmanagement in the past has been directed towards the detection of early (pre-cancerous) changes within the cervix through a cervical screening program (regular pap smears).
In short, yes I hear that having pap smears are a bit of a nightmare, but it can save your life. If you are sexually active, you should have a pap smear every year (unless there is an abnormality in which case your doc will suggest more often).
Can HPV infection be prevented?
The HPV vaccine now offers an opportunity to prevent infection with high-risk HPV & thus significantly reduces the risk of cervical cancer & genital warts.
The HPV vaccine prevents infection by preventing the virus from entering the cells.
There are two registered HPV vaccines on the market:
1. Gardasil: vaccine active against HPV strains 6, 11, 16, 18 (http://www.gardasil.com/)
2. Cervarix: vaccine which is active against HPV strains 16 & 18 (http://www.cervarix.ca/)
HPV vaccine safety:
Both HPV vaccines do not use live virus. It is made up of proteins that imitate the outer shell the virus and trigger an immune response that protects against infection with the particular HPV type.
(Before medicine is released, it goes through 4 stages of clinical trials for safety which take many years. First it gets tested in laboratories, then on animals and if all those hurdles are passed, it gets tested on people).
Prior to making the drug available on the open market, more than 60 000 women who received the vaccine were monitored for undesirable side effects events following exposure to vaccine.
Less than 1% of women developed fever, nausea & dizziness following vaccination. Trial participants were followed until 15 months, with no increase in a newly diagnosed chronic illness, auto-immune disease or severe medical condition.
The pharmaceutical companies have to be super careful because if anything happens they will incur law suits which will cost major bucks.
As of December 2008, more than 23 million doses of HPV vaccine had been administered in the USA. The most frequently reported events that are reported are local injection site reactions (e.g. rash on the arm), nausea, dizziness and fainting. These pass.
No link between the vaccine and serious unfavorable side effects has been demonstrated in the USA.
In Australia, as of March 2009, 5 million doses of HPV vaccine had been administered. In Australia the most important unfavorable events following vaccine were allergic reaction ( 11 cases) and convulsions (18 cases). These are extremely rare events, occurring in less than 1 in 100 000 cases.
Remember one can have an allergic reaction to anything – e.g.bee stings, shell fish (etc)
In Germany, as of March 2008, more than 2 million doses of HPV vaccine had been administered. In Germany, two incidents of temporary facial paralisis, one case of Guillain-Barré-Syndrome have been reported.
Again, these are extremely rare events.
In short you have more chance of getting cervical cancer if sexually active than of having a reaction against the vaccine.
The official standpoint of numerous national & international agencies (including the WHO http://www.who.int/wer/2009/wer8415.pdf ) is that the vaccines are safe and effective.
How effective are the vaccines?
The development of the HPV vaccine is a landmark in the history of immunization, since this is the first anti-cancer vaccine.
I believe this vaccine will be given widely when we are all grandparents. I hope it catches on quicker though. The polio vaccine was not given universally when our grandparents were young but is widely given to children now days.
The two presently available vaccines have been proven effective in the prevention of pre-cancerous lesions and can exert their maximum efficiency if used at pre-adolescent age, when sexual activity has not yet started.
pictures from http://www.weheartit.com/