SPIEGEL: For a number of years, as part of the Cochrane Collaboration, you have been systematically evaluating all the studies on immunization against seasonal influenza. How good does it work?
Jefferson: Not particularly good. An influenza vaccine is not working for the majority of influenza-like illnesses because it is only designed to combat influenza viruses. For that reason, the vaccine changes nothing when it comes to the heightened mortality rate during the winter months. And, even in the best of cases, the vaccine only works against influenza viruses to a limited degree. Among other things, there is always the danger that the flu virus in circulation will have changed by the time that the vaccine product is finished with the result that, in the worst case, the vaccine will be totally ineffectual. In the best of cases, the few decent studies that exist show that the vaccine mainly works with healthy young adults. With children and the elderly, it only helps a little, if at all.
SPIEGEL: But aren't those the exact groups that influenza immunization is recommended for?
Jefferson: Indeed. That's one of the contradictions between scientific findings and practice, between evidence and policy.
SPIEGEL: So, what's behind this contradiction?
Jefferson: Of course, that has something to do with the influence of the pharmaceutical industry. But it also has to do with the fact that the importance of influenza is completely overestimated. It has to do with research funds, power, influence and scientific reputations!