Tom Jefferson is a medically trained epidemiologist and Cochrane reviewer who has a specialist research interest in the effectiveness of vaccinations. As the first press releases start to filter through about vaccinations for H1N1, there are numerous questions in my mind as to the usefulness of this vaccine – not just for people in general, but for people at higher risk or who work in the health service and are going to be recommended to have it .
MM: As someone who has examined the evidence on this topic, Tom, I’m wondering what your thoughts are as to the potential role of influenza vaccination in a “pandemic”?
TJ: First, let me say that all our reviews are freely available online at cochrane.org site – click on resources. [Some of the vaccine studies Dr Jefferson has been involved can be found on the Wiley Interscience site]. The question you are really asking is – how effective are seasonal vaccines? And our reviews either show no effect or limited effect, and poor data.
What is interesting is that there has been extensive manipulations of the visibility of the data. Now, if you take influenza related mortality in the US – deaths related to influenza, bilateral pneumonia and so on – if you take the CDC (Centre for Disease Control and Prevention) data over the past 20 years, the curve is flat. A plateau. That line flattened after the 1950s – but before influenza vaccination started. As in – influenza related mortality crashed for reasons independent of vaccines. But, if you look at the past 20 years, the mean impact factor of journals (how well read, or well cited they are) the line is nearly vertical. These are pharma sponsored studies. But as far as seasonal influenza vaccines go, there is no difference to the level of threat from 20 years ago. But influenza vaccines have become the thing to talk about – they are now the things that journals like to run.
MM: Pandemic flu vaccines are currently in development; do we know much about them?
TJ: I have consulted the meta-register of clinical trials which should contain registration and broad outline of all current, recently closed or about to begin clinical trials on (in this case) H1N1 vaccines. I have found nine studies on H1N1 so-called pandemic vaccines using the search string “influenza H1N1″. However none of these studies are completed (except for H1N1 trials for “FluMist”, which is an error as it is another type of non pandemic vaccine). Some of them have not even started. The ones that have, give a completion date of Dec 2010.
I have also consulted the International Federation of Pharmaceutical Manufacturers & Associations IFPMA clinical trials portal and found a further 8 trials of H1N1 all similarly either ongoing or recruiting. These too have delivery dates of late 2009-2010. Note that the vast majority of these trials are financed by public money. What we would need to do is to go through each entry tabulating the details to be absolutely certain of the facts.
MM: So what kind of testing should there be on new H1N1 influenza vaccines before they are used widely?
TJ: Do we know they are safe, or what the side effect profile is? No, we don’t. We rely on forecasting with seasonal influenza vaccine – and some safety things – like injection site marks – and on past performance. The best evidence we have is for use in healthy adults - where there’s limited benefit – and there is none for use in pregnancy, yet.
Do we have a mechanism for dealing with vaccines which perform poorly or not at all? Not evidently. Do we know if these pandemic flu vaccines will do better? We don’t.
MM: A number of questionnnaires in the UK suggest many doctors and nurses will decline to receive any new pandemic flu vaccine against H1N1. But doctor and nurse leaders have asserted that they should have it in order to protect patients. I have seen no evidence that leads me to think that me being vaccinated will make much difference – what do you think?
TJ: There is no evidence, looking at seasonal flu vaccines, that is going to do anything – to benefit the elderly or others. There is evidence that healthcare workers may be prevented from symptoms of the flu, but these workers having the vaccine do not show a decrease in mortality. The data are poor.
MM: Thank you: much appreciated.
There are several podcasts featuring Dr Jefferson on the Cochrane website for further information: Cochrane Influenza Resources