There is an astounding figure that keeps popping up in regards to the seasonal flu: you are half as likely to die – of any cause – if you submit to the flu vaccine. Wow, with numbers like that, I may just get vaccinated every week! How could anyone pass up a shot that cuts your chance of dying in half?
Because when things seem too good to be true, they usually are.
This figure is at best misleading, and at worst flat out wrong. In the words of Tom Jefferson, head of the Vaccines Field at the Cochrane Collaboration, "For a vaccine to reduce mortality by 50%…means it has to prevent deaths not just from influenza, but also from falls, fires, heart disease, strokes, and car accidents. That's not a vaccine, it's a miracle."
One big problem with figures like these is that they tend to ignore factors like education and lifestyle – "confounding" factors that are difficult to measure and predict.
A study from Alberta, Canada aimed to eliminate some of these confounding factors. They split 704 elderly patients into two groups, one of which had gotten a flu shot and one had not. They adjusted for criteria that had been ignored in other studies – like education, income and social status – and concluded that the vaccine's ability to keep the elderly alive was, "if present at all...very small and statistically non-significant and may simply be a healthy- user artifact that they were unable to identify".
This "healthy user effect" is attributed to those people who eat right, don't smoke, get regular check ups and – in keeping with the conventional doctor's dogma – consistently get vaccinated. So they tend to be in better health and live longer, skewing the vaccinations efficacy stats.
There is another group that distorts the studies as well: people who are simply too sick to get the vaccine, but are still counted in the non-vaccinated group. Given their weakened condition, they are much more likely to pass away – so up goes the non-vaccinated death toll, skewing the results even further!
Results like those in the Alberta study may begin to challenge the "double your survival" stats touted by vaccine proponents.
Thursday, November 05, 2009
Comment on Flu Data Double Speak
This comment just arrived from a journalistic colleague, and it makes some very good sense.