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Human papillomavirus (HPV) vaccination

Posted Aug 19 2009 10:24pm
HPV vaccination is getting more and more popular these days.

It is not limited to female, but to male, now, to provide protection against human papillomavirus (HPV). (For male, it's still an unlabelled use, and they claimed that it will help spread the HPV if the vaccination extended to male population)

HPV can cause cervical cancer is discovered by Zur Hansen, the winner of Noble Prize in Physiology or Medicine in 2008.

So, the pharmaceutical companies started to develop vaccines for HPV. The theory is: If you can prevent HPV, you can prevent cervical cancer, too.

So simple? I wish so.

However, there are more than 100 types of HPV (and a study discovered that some of them are linked with development of hypertension too, so, that means vaccination for hypertension in the future?), and at least 15 of them are oncogenic.

Current vaccines only cover some of them:
  • Gardasil (from Merck & Co) covers type 16, 18, 6 and 11
  • Cervarix (from GSK) covers type 16, 18
HPV is the most prevalence sexually transmitted disease, however, the virus does not appear to be very harmful as most of them can be cleared by our immune system.

Only for some women, the infection will persist, and eventually develop into cervical cancer. However, till now, we do not have any tool or method to predict what type of woman will have such tendency.

As we cannot predict who will develop cervical cancer, we also cannot predict the effect of vaccine on the young girls and women, 20 or 40 years from now. We can only see the effect using long term clinical trial or follow-up.

Right now, what we have is studies on prevalence of cervical intraepithelial neoplasias grades 2 and 3.

There were adverse events reported on HPV vaccines, mostly on dizziness, headaches, and fever. Not very serious. There were also some serious events such as anaphylaxis, Guillain-Barre syndrome, transverse myelitis, pancreatitis, and venous thromboembolic events. However, we cannot conclude whether these adverse reactions were caused solely by the vaccines, or not.

The situations we are facing now, are:
  1. We do not know the net benefit of the HPV vaccines
  2. We do not know the long term harmful effect of these vaccines either
For medical professional judgement, we tend to weigh between benefits and risks, then to conclude whether a medical decision is sound, or not.

Now, how can we decide?

Economically, we look at the incentives.

If you are a woman/man, plan to live sexually active in the future (having multiple sex partners), taking the vaccine is definitely a good choice. But who will know what kind of life you will have in the future anyway?

And if you are already sexually active, it's already too late to have the vaccines.

And even if you already took the vaccine, it's not a guarantee that you are free from cervical cancer 100% throughout your life. You still need to do regular screening.

So, you should think about the cost (including the potential harmful effects) of the vaccines. before you take it.

How about consulting healthcare professionals?

Well, they are judging whether to take the vaccine, by weighing benefits vs risks as well. And it is important to ask who takes the risk, and who gets the benefits. Indeed.

(Take note that the so-called healthcare professionals' judgement are always clouded by the promotion strategies by pharmaceutical companies)

So, what's the conclusion?

The truth is, I don't have one for you. Sorry.
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