BTO: Clearing the air on HPV vaccines

Business Times - 11 Apr 2009

Clearing the air on HPV vaccines

Debate surrounding cervical cancer prevention jabs have created confusion over who should get it. By Cheah Ui-Hoon

 

CERVICAL cancer vaccination has been in the news lately, though all the debate surrounding it might have created some confusion. Some questions floating about include whether it's safe, and whether women older than 26 should also be vaccinated.

 

Harald zur Hausen, winner of the Nobel Prize for Physiology or Medicine for his discovery of the cause of cervical cancer clears the air on these issues, at the inaugural Asian Oncology Summit last week.

 

Guidelines for cervical cancer prevention jabs apply to females from nine years old to 26, but some doctors here have been administering them to older women as well.

 

Prof zur Hausen's verdict is that as long as women have had sexual relations, it exposes her to human papillomavirus (HPV), so that renders the vaccination ineffective.

 

'It makes sense for women older than 26 to have the jab only if they aren't already infected with the virus types. It doesn't make sense if they're already infected,' he points out. And exposure to this virus is largely through sexual contact. This is because the vaccine is clearly preventative, so it doesn't protect someone who's already contracted the virus. 'What vaccination does is to produce antibodies which penetrate into the tissue, and inactivates the virus prior to its entering the cell. If the virus has already entered the cell, they no longer present the same types of proteins,' he explains. Tests to screen if someone has HPV are also not trustworthy, and even if results are negative, a person might already have been infected, Prof zur Hausen adds.

 

'It's those who have not been exposed to sexual contact before who can profit from this vaccine, irrespective of age,' he says. He adds that in some countries, the vaccination age should even be as low as seven to nine years, because of the earlier age of sexual activity.

As for adverse effects reported about the vaccine, Prof zur Hausen says that based on data, the vaccine isn't more risky than other vaccines provided to small children. 'Of course, no vaccine is without any risk,' he says. More support should be given for research into infectious cancer viruses, he advocates, because at the moment, about 20 per cent of global cancer incidents is due to infections. These include Hepatitis B and C, and also bacterial infections like helicobacter pylori which increases the risk of stomach cancer. 'The more causes of cancer we identify, the higher the possibility of scientists coming up with preventive medicine,' he concludes.