More on the HPV vaccine

[moominmuppet]

One of the open questions about Gardasil has been how well it protects people who've already been exposed to one or more of the strains of HPV. Unfortunately, it looks like the results aren't the best we could hope for, although I agree with the critique that it's hard to tell from such relatively short studies how much long term benefit we may see, given that cervical cancer generally takes quite a while to develop. Still, it's looking like a pretty strong argument for early vaccination, prior to first exposure.

Public Health & Education | Efficacy of HPV Vaccine Gardasil Among Women Previously Infected With HPV Lower Than Expected, Study Says

That'll be about it from me today, I expect. I'm leaving early for the second part of my root canal, and in the meantime I have some important email to write, and a callback from the vet coming in.

Comments

[lilyofthewest.livejournal.com]

The question isn't so much *if* it would be effective, but *how* effective it would be.

The vaccine protects against 4 different strains of the virus -- 2 dramatically increase the odds of cervical cancer, 2 that can cause genital warts.

The study that the article linked to above is talking about found that while almost all of the women who had previously been sexually active had been exposed to at least one of the strains, only 1% had been exposed to all four.

The vaccine protects *very* well against any strains you don't already have. If you already have one of the strains that the vaccine is for, it may not help. It might help boost immune response to the virus, but not necessarily, and not necessarily substantially.

The Merck spin on these poor results has been unconscionable.

[(Anonymous)]

The problem is that the GARDASIL has not been proven safe or effective for its targeted population of preteens.

Furthermore, there is NO CLINICAL EVIDENCE WHATSOEVER that GARDASIL reduces the overall rates of type 3 dysplasias or adenocarcinomas among the general population of women aged 16 to 26. See: http://content.nejm.org/cgi/content/full/356/19/1991

To summarize this publish medical journal article:

1. In the FUTURE I trial, GARDASIL demonstrated no clinical efficacy among the general subject population for overall reduction in the rates of grade 2 and grade 3 cervical intraepithelial neoplasia and adenocarcinoma -- the only recognized precursors to cervical cancer.

2. In the larger FUTURE II trial, GARDASIL demonstrated no clinical efficacy among the general subject population for overall reduction in the rates of grade 3 cervical intraepithelial neoplasia and adenocarcinoma -- the strongest (and many would argue only valid) precursors to cervical cancer.

3. Extrapolating from GARDASIL's very limited clinical "success" (in the FUTURE II study only) against grade 2 cervical dysplasias (40% of which regress spontaneously), 129 women would be have to be vaccinated (at a cost of about $60,000) to prevent a single grade 2 cervical dysplasia.

4. GARDASIL's protection against cancer associated HPV strains 16 and 18 appears to cause a disproportionate increase in of pre-cancerous dysplasias associated with other HPV strains associated with cervical cancer "raising the possibility that other oncogenic HPV types eventually filled the biologic niche left behind after the elimination of HPV types 16 and 18."

5. Even if you segregate out the women who hadn't been previously exposed to either HPV 16 or 18, we are talking about just a 17% decrease in all high grade dysplasias (266 out of 6080 vs. 219 out of 6087) -- many of which would spontaneously regress without treatment. So we would have vaccinate 129 women (at about $500 for the three shot regimen) to avoid a single dysplasia. That's about $60,000 per dysplasia prevented.

6. We currently have only 3 years of follow up to go on in terms of both GARDASIL's safety and efficacy, no data concerning its efficacy among 9 to 12 year olds and only 18 months of follow up on less than 600 total preteen girls in terms of safety data concerning GARDASIL within its targeted population.