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Influensa vacciner verkar ha tveksam, om än någon, effekt på de förekommande virus som vi erbjuds vaccinationer för.15 av 36 studier, vilka visade på nytta med vaccinationer, var betalda av läkemedelsindustrin.
Läkemedelsindustrifinansierade studier, var oftare än andra publicerade i ansedda medicinska journaler och citerades oftare, trots att de hade svåra studiekvalitetsmässiga brister och att underlaget ofta var tunnt.
Allmänt finansierade studier var mer tveksamma till vaccinernas nytta.
Vaccines for preventing influenza in healthy adults (Review)
Jefferson T, Di Pietrantonj C, Rivetti A, Bawazeer GA, Al-Ansary LA, Ferroni E
Authors? conclusions
Influenza vaccines have a modest effect in reducing influenza symptoms and working days lost. There is no evidence that they affect
complications, such as pneumonia, or transmission.
WARNING:
This review includes 15 out of 36 trials funded by industry (four had no funding declaration). An earlier systematic review of 274
influenza vaccine studies published up to 2007 found industry funded studies were published in more prestigious journals and cited
more than other studies independently from methodological quality and size. Studies funded from public sources were significantly
less likely to report conclusions favorable to the vaccines. The review showed that reliable evidence on influenza vaccines is thin but
there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies. The content and conclusions of this
review should be interpreted in light of this finding.
P L A I N L A N G U A G E S U M M A R Y
Vaccines to prevent influenza in healthy adults
Over 200 viruses cause influenza and influenza-like illness which produce the same symptoms (fever, headache, aches and pains, cough
and runny noses). Without laboratory tests, doctors cannot tell the two illnesses apart. Both last for days and rarely lead to death or
serious illness. At best, vaccines might be effective against only influenza A and B, which represent about 10% of all circulating viruses.
Each year, the World Health Organization recommends which viral strains should be included in vaccinations for the forthcoming
season.
Authors of this review assessed all trials that compared vaccinated people with unvaccinated people. The combined results of these
trials showed that under ideal conditions (vaccine completely matching circulating viral configuration) 33 healthy adults need to be
vaccinated to avoid one set of influenza symptoms. In average conditions (partially matching vaccine) 100 people need to be vaccinated
to avoid one set of influenza symptoms. Vaccine use did not affect the number of people hospitalised or working days lost but caused
one case of Guillian-Barré syndrome (a major neurological condition leading to paralysis) for every one million vaccinations. Fifteen of
the 36 trials were funded by vaccine companies and four had no funding declaration. Our results may be an optimistic estimate because
company-sponsored influenza vaccines trials tend to produce results favorable to their products and some of the evidence comes from
trials carried out in ideal viral circulation and matching conditions and because the harms evidence base is limited..
