Here is a 2014 Cochrane Report on
Vaccines for preventing influenza in healthy adults
The preventive effect of parenteral inactivated influenza vaccine on healthy adults is small: at least 40 people would need vaccination to avoid one ILI case (95% confidence interval (CI) 26 to 128) and 71 people would need vaccination to prevent one case of influenza (95% CI 64 to 80). Vaccination shows no appreciable effect on working days lost or hospitalisation. The protection against ILI that is given by the administration of inactivated influenza vaccine to pregnant women is uncertain or at least very limited; the effect on their newborns is not statistically significant. The effectiveness of live aerosol vaccines on healthy adults is similar to inactivated vaccines: 46 people (95% CI 29 to 115) would need immunisation to avoid one ILI case.
The administration of seasonal inactivated influenza vaccine is not associated with the onset of multiple sclerosis, optic neuritis (inflammation of the optic nerve of the eye) or immune thrombocytopaenic purpura (a disease that affects blood platelets). The administration of pandemic monovalent H1N1 inactivated vaccine is not associated with Guillain-Barré syndrome (a disease that affects the nerves of the limbs and body).
Evidence suggests that the administration of both seasonal and 2009 pandemic vaccines during pregnancy has no significant effect on abortion or neonatal death.
Quality of the evidence
The real impact of biases could not be determined for about 70% of the included studies (e.g. insufficient reporting details, very different scores among the items evaluated). About 20% of the included studies (mainly cohorts) had a high risk of bias. Just under 10% had good methodological quality.”
OK, so the Cochrane reports that it takes a lot of flu vaccines to prevent any influenza, and the evidence demonstrating even this gain is fairly crummy, so maybe it might not be real at all. They found no appreciable impact on working days, for example.
Kind of a contrast to the constant media blitz.
But here’s my problem with this: its hellaciously optimistic. It assesses the benefits of the vaccine, and finds them minimal if that, but IMO it doesn’t adequately assess the costs.
The costs I would worry about most, would be that the vaccine might damage the immune systems of the recipients, and that mercury or contaminants in the vaccines might add to total load and cause long term problems. Previous posts here have suggested these possibilities should not be overlooked.
I have not seen research I would say shows these things are happening, but also I haven’t seen the long term studies I think there should be asking the question either, so I have no confidence they aren’t happening. They represent a risk, IMO.
I think its worth pointing out that the Cochrane, pessimistic as it is, is not based on studies looking at long term health.
If the vaccine were to damage your immune system, you may suffer from that every year till you die.
If the total metal load is a problem, you may suffer from that every year till you die.
Any conceivable benefit of the flu vaccine, however, is almost certain to come in the first year, because after that the flu strain will have moved on.
I would like to see studies on flu vaccine recipients’ health in the 2nd year after the vaccine.
There is a bias in the literature, that these extended costs are not being considered, so far as I can tell, in cost-benefit estimates of the value of the vaccines.