Tuesday, August 4, 2009

Australia Approves Gardasil for Women Up to Age 45

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Australia’s Therapeutic Goods Administration (TGA), roughly the equivalent of the United States’ FDA, has approved the Gardasil vaccine for use by women up to age 45. Previously, it had been approved only for ages 9-26. The vaccine was developed by Professor Ian Frazer, who was named Australian of the Year in 2006.

Earlier this year the FDA refused to allow Gardasil to be used in older women, citing the need for completion of an ongoing 48-month study and an analysis of the data.

The FDA’s caution may well spring from background information provided for the Vaccines and Related Biological Products Advisory Committee (VRBPAC) back in May 2006. The Committee was extremely concerned about data that showed that when the vaccine is given to a woman with a dormant or harmless form of HPV, the virus can become activated, increasing the likelihood of precancerous lesions developing by a startling 44.6 percent. The vaccine does not clear existing infections.

The TGA’s decision was likely spurred by a recent Columbian study funded by Gardasil maker Merck. It found that the vaccine was 91 percent effective in preventing new infections in women aged 24-45 if—and this is a big 'if'—they had never previously had HPV or cervical disease. The Australian public health service will not provide the vaccine free of charge for women under or over the ages of 12-26 as it clearly is not cost-effective, recommending instead that women continue to be vigilant about getting regular Pap smears.

Gardasil protects against two cancer-causing strains and two genital-wart causing strains of human papillomavirus (HPV). There are thought to be more than 100 strains of HPV, about 40 of which can cause cancer, and about 80 percent of the population will be infected with it at some point in their life. Some 95 percent of infections are shrugged off by the body within about 18 months, leaving a natural immunity to that strain. Only persistent infections can cause the lesions that might eventually become cervical cancer. Most lesions are easily detected during an annual Pap smear test in developed nations, although cervical cancer is a major killer in some countries where women do not have access to routine health care.

2 comments:

Darren said...

I'd like to point out here that the 44.6% value you quote here is misleading. Please read through the actual results here on pages 13-15 (hosted by the highly anti-vax Natural News).

That 44.6% figure was suspected to be due to issues with sample selection, and a replication with better sampling found a slight reduction in lesions using Gardasil (however, much less than with uninfected women, as expected).

Darren

Kristin Johns said...

Thanks very much for your comment: this figure has been puzzling me as I hadn't found a previous explanation for it and it seemed unduly reckless not to require HPV tests prior to vaccination.

However, I don't find the re-analysis you reference particularly comforting. After piddling around with the figures and balancing out people with enhanced risk factors such as smoking, new sub-groups showed enhancement of disease by 'only' 33.7 percent, then a minor reduction by 5.4 percent, and then with a combined study figure as an overall enhancement of disease of 11.7 percent.

Maybe I'm crazy, but me, I'd look at these figures and get an HPV test prior to bothering with vaccination. It seems to me that at best the vaccination would be more or less useless and at worst possibly dangerous if one already had HPV, as so many sexually active women do. And in any case, it certainly wouldn't be remotely cost-effective. No wonder the Australian government isn't paying for it for older women.

One other point. Why are Merck et al so remarkably quiet about smoking as a known risk factor for cervical cancer? I've never found an answer to that, either. K