Vaccines For Preventing Influenza In Healthy Adults, Cochrane Database of Systematic Reviews, July, 2010
- There are over 200 viruses and agents that cause influenza. The flu vaccine covers up to 15% of those.
- "4% of unvaccinated people versus 1% of vaccinated people developed influenza symptoms." (So, 96% of people who didn't get a flu shot avoided getting the flu on their own, when exposed.)
- "Vaccination had no effect on hospital admissions or complication rates."
- "We found no evidence that vaccinations prevent viral transmissions."
- "Inactivated vaccines caused local harms and an estimated 1.6 additional cases of Guillain-Barré Syndrome (a form of progressive paralysis) per million vaccinations."
- "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."
This Cochrane Review included one of the largest collections of randomized evidence on influenza. It consisted of 36 trials, 15 of which were conducted by industry and, given the last point above, were likely biased. The Review still found no evidence of benefit for hospital admissions, flu complications, or transmission rates, and only a weak benefit for symptom reduction.
I've been noncommittal about the flu vaccine thinking it doesn't hurt and might help. It's difficult to remain noncommittal when an independent, international, evidence-based group of researchers says:
"The results of this review seem to discourage the utilization of vaccination against influenza in healthy adults as a routine public health measure."Here's Tom Jefferson from the Cochrane Vaccines Field describing the findings: