By Alison Campbell 08/07/2019

New Zealand’s measles outbreak keeps on ticking along. So do the media stories about it. (The FB posts associated with each article aren’t moderated and I suspect this is partly because they generate so many clicks.)

A couple of days ago, TVNZ’s Breakfast show carried an interview with a doctor, on the importance of Gardasil, a vaccine that offers protection against several strains of HPV (Human Papilloma Virus). This virus is causally implicated in the development of cervical cancer, genital warts, penile & anal cancer, and some cancers of the mouth and throat. So anything that can reduce rates of infection with the virus will have an impact on the rates of these cancers further down the track. The news story came on the heels of a new paper (summarised here): a meta-analysis of research on Gardasil’s effectiveness that shows significant drops in rates of HPV infection in the vaccinated cohorts.

Anyway, as you might expect, the anti-vaccine activists are all over the story’s FB post. And thus it was that I was alerted to a new “study” by an Italian group, Corvelva, which purports to show that Gardasil contains a number of contaminants, including foreign DNA. (You’ll see why I wrote “study” shortly.)

Now, Corvelva has “published” several documents setting out their findings¹. I say “published”, because as far as I can tell their reports exist as on-line pdfs only. That is, they haven’t been through even the rudimentary peer-review process associated with bottom-tier journals, such as those in the OMICs stable. Rather surprisingly, the document hasn’t listed the names of those who wrote it.

The document leaps straight into their results, and yes, up-front they look alarming. The Corvelva group claim to have found both DNA and RNA, from a wide range of sources, as contaminants in the vaccine.

However, it’s not obvious that they used controls in this study. So there’s no way of telling whether or not there were any external contaminants present e.g. DNA shed by workers in the lab. Certainly a lot of the contaminants they claim to have found in their Gardasil samples are from bacteria that are part of the human microbiome, and without proper controls it’s not possible to draw conclusions about where they came from. (There’s a discussion about the nature of appropriate controls here.)

There is no statistical treatment of the results.

There is no discussion – that important section of a report that puts the findings in context, and relates those results to those of other workers in the field. Come to that, there’s no attempt to link to relevant research literature at all, just a very scanty (N = 3) “Bibliographic references” section that relates to sequencing techniques. Heck, they even say things like “see research by Prof. Lee”, but provide no citation at all²! Honestly, if a first-year uni student submitted a write-up like this they’d get a big fat F for it.

Anyway, I said all this (albeit more briefly) on that particular thread on the Breakfast story. (Plus some comments on other statements by the same individual.)

The response (below, & I’m leaving it complete given it was made on a public page) rather effectively reinforced my impression that many anti-vaccine activists plague enthusiasts really don’t understand the scientific research process at all.

Suuuure I’m denying “inconvenient science”, Karen³.


¹ The Skeptical Raptor has had a more detailed look at Corvelva’s output (see here, for example).

² Although, I have my suspicions as to who this might be.

³ Karen mentions “the BMJ article just published that speaks to the clinical trials and how adverse events were minimised or ignored”. She helpfully does not provide any link to this. (Also, since many BMJ articles – both research papers and editorials – are behind paywalls, I’m not sure if she’s read more than an abstract.) Fairly sure it’s not this editorial, though. But here’s the list of research papers published in the British Medical Journal in May & June this year.


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