Tapu Misa: When a shot in the arm's no silver bullet

The TV advertising campaign for the "anti-cancer vaccine" Gardasil makes it look like a no-brainer. "It's your choice," the ads say about the vaccine that's now being offered free in our schools to girls aged from 12 to 18. But it sounds more like no choice. What caring parent wouldn't choose to vaccinate her daughter from a potentially deadly cancer when three shots are "all it takes to protect her from cervical cancer".

You'd have to be a pretty bad mother not to encourage your daughter to get vaccinated.

There's no doubting the persuasive power of the marketing campaign that was launched here in early 2007, not long after Medsafe had approved Gardasil's use in New Zealand.

In the US, a slick advertising campaign funded by Merck, Gardasil's maker, was unleashed on American mothers and teenage girls even before the FDA had fast-tracked its approval of the vaccine. The ads stressed the link between the common virus, HPV, and cervical cancer - exaggerating the threat of girls getting what the National Institute of Health refers to as "a rare disease". Award-winning TV ads since then have made vaccination seem like the latest must-have accessory no American girl can live without.

And maybe it is. Information put out by the Ministry of Health says Gardasil is safe, that it protects against 70 per cent of cervical cancers, and that it's been licensed for use in over 100 countries around the world including Australia, the US, Canada and the UK.

It's also very expensive. The immunisation programme announced by the previous Government - two months before the last election - was costed at $177 million over the next five years, with an ongoing price tag of $16 million a year.

To say that this money might be better spent elsewhere - say, in treating actual cancers and other diseases - would seem heartless when estimates put the number of lives saved at around 30 a year.

But as women's health advocate Lynda Williams has pointed out, it will take 20 years before we know for sure if Gardasil is the life-saving "anti-cancer vaccine" it's been hyped up to be, because it takes around 15 years for cervical cancer to develop - and the trials weren't long enough to tell us that. There's no guarantee, either, that the vaccine will provide immunity for longer than five years, which means expensive booster shots may be needed.

Certainly, the vaccine has already been a lifesaver for Merck, which needed an infusion after it was forced to withdraw its anti-arthritis drug Vioxx from the market. Merck now faces 11,500 lawsuits after Vioxx - which had also been fast-tracked by the FDA - was found to increase the risk of heart attacks and strokes.

A cynic might see a link between this and the drug company's aggressive lobbying to make Gardasil mandatory for girls in the US. The New York Times reported last year that 24 states had put forward proposals requiring the vaccine for girls in middle school. Vaccination is now a requirement of school entry in Virginia, but a similar move was overturned by the Texas legislature after it was found that Merck had hired the Texas governor's chief of staff as a lobbyist, and made financial contributions to the governor.

As a 2007 article in the Wall Street Journal observed: "Mandatory vaccination across the US would make an automatic blockbuster for Merck at a time when the patents on some of its bestselling drugs are expiring and it's desperate to replace their revenue streams."

The HPV virus that causes 99 per cent of cervical cancers is transmitted through sexual contact. The vast majority of sexually active women can expect to be infected by HPV at some time in their lives, but most of these infections clear up on their own. Only a small proportion will lead to cancer. Trials show that Gardasil is effective against the two types of HPV that cause up to 70 per cent of all cervical cancers.

But as an August 2008 editorial in the New England Journal of Medicine points out, there are reasons for caution. "The bad news is that the overall effect of the vaccines on cervical cancer remains unknown ... the real impact of HPV vaccination ... will not be observable for decades." In other words, just because Gardasil has been shown to be highly successful in preventing pre-cancerous lesions caused by HPV doesn't mean that the vaccine will ultimately prevent cervical cancer and death.

Indeed, a number of "critical questions remained unanswered". For instance, since most HPV infections are easily cleared by the immune system, how would vaccination affect natural immunity against HPV, and with what implications? How long would protection last? How would the vaccine affect pre-adolescent girls, given that the clinical studies didn't include girls under 16?

And might the suppression of HPV16 and HPV18, the two types of HPV targeted by Gardasil, make room for other cancer-causing strains to emerge in their place? Published reports of trials suggest just such a trend.

There've been safety concerns, too - claims that Gardasil has caused serious illness and even death - although no causal link has been proven.

Of concern, too, is the effect mass vaccination will have on what is still the most effective weapon against cervical cancer: prevention, not through a vaccine, which may head off only 70 per cent of cancers, but through regular cervical smears with a proven 90 per cent success rate.

Gardasil doesn't do away with the need for the smears, and it doesn't protect for life. But the false sense of security it gives girls may well cost them their lives.

* Tapu.Misa@gmail.com