The Cochrane reviews on HPV vaccines - Part 2

How to mix up results to get a “right" press release

In our first post, we looked at the review of observational data. Now we turn to the review of randomised controlled trials.

However, before we focus on the results, let’s look at what the Press release states:

Two claims stand out: strong, consistent evidence and the vaccines’ effectiveness in preventing cervical cancer.

As for the first claim, it can’t be the observational review, as it reported a serious risk of bias due to confounding by observational evidence. Here’s how Cochrane put it:

‘The observational and retrospective designs of most studies contributed to the high risk of bias. In retrospective studies, controlling for confounding between vaccinated and unvaccinated groups becomes challenging, especially when additional characteristics of the population are unknown or unrecorded.’

However, the Review does return a result consistent with the idea that they are effective in preventing high‐grade CIN and cervical cancer.

The review of RCTs examined Cervarix, Gardasil, Gardasil-9, …