Cochrane review and flu vaccines

[Rrrrrachel]

I've seen the assertion several times lately that the flu shot is ineffective, and even the cochrane review says so. I just wanted to point out that the cochrane review says no such thing. They have done two review, one for healthy adults and one for healthy children. They did say that for children under two inactivated vaccine was similar to placebo, but that's a long way from a blanket statement saying flu vaccines are ineffective.

http://summaries.cochrane.org/CD001269/vaccines-to-prevent-influenza-in-healthy-adults

http://summaries.cochrane.org/CD004879/vaccines-for-preventing-influenza-in-healthy-children

[Eligracey]

Thanks for posting this! Cochrane reviews are really the scientific gold standard.

[Turquesa]

Since I'm guessing you haven't read either review in its entirety, why don't you find out from the author himself has to say about his own research? He could not find quality evidence that the flu vax was effective in the under-2 group.

http://focusonline.ca/?q=node/447

I'm questioning whether you'll read the link before replying, but at least it's there for someone else's reference.

[Rrrrrachel]

Isn't that what I said?

[Turquesa]

No. You said that it's a long way from saying that the flu vax is ineffective. The Cochrane scholar disagrees with you. He says they're ineffective.

[Turquesa]

And actually, they've done more than 2 reviews. The flu vax is ineffective for the elderly, asthmatics, health care workers, and other high-risk populations.

[Rrrrrachel]

Right, ineffective for children under two. That's not the same as a blanket statement that they're not effective across the board.

[kathymuggle]

From Cochrane:

http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001269.pub4/abstract;jsessionid=6CB5626A8606B3497E397AD984676298.d03t03

"...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."

Bolding mine.

[Rrrrrachel]

But it is effective at preventing the flu.

[Rrrrrachel]

Originally Posted by Turquesa 

And actually, they've done more than 2 reviews. The flu vax is ineffective for the elderly, asthmatics, health care workers, and other high-risk populations.

I missed this the first time. I disagree with some of the characterization a here, but as they're more nuanced than a blanket state my that it's ineffective it's more a matter of opinion and interpretation.

[MamaMunchkin]

Originally Posted by Rrrrrachel 

I've seen the assertion several times lately that the flu shot is ineffective, and even the cochrane review says so. I just wanted to point out that the cochrane review says no such thing. They have done two review, one for healthy adults and one for healthy children. They did say that for children under two inactivated vaccine was similar to placebo, but that's a long way from a blanket statement saying flu vaccines are ineffective.
http://summaries.cochrane.org/CD001269/vaccines-to-prevent-influenza-in-healthy-adults
http://summaries.cochrane.org/CD004879/vaccines-for-preventing-influenza-in-healthy-children

It seems the problem might be more than just the vax being ineffective for <2-yr old, at least from these links ...

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From the first link -  click on Abstract (click to read) at the bottom ...

http://summaries.cochrane.org/CD001269/vaccines-to-prevent-influenza-in-healthy-adults

 

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.

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From the second link - click on Abstract (click to read) at the bottom ...

http://summaries.cochrane.org/CD004879/vaccines-for-preventing-influenza-in-healthy-children

 

Authors' conclusions: 

Influenza vaccines are efficacious in preventing cases of influenza in children older than two years of age, but little evidence is available for children younger than two years of age. There was a difference between vaccine efficacy and effectiveness, partly due to differing datasets, settings and viral circulation patterns. No safety comparisons could be carried out, emphasising the need for standardisation of methods and presentation of vaccine safety data in future studies. In specific cases, influenza vaccines were associated with serious harms such as narcolepsy and febrile convulsions. It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months of age in the USA, Canada, parts of Europe and Australia. If immunisation in children is to be recommended as a public health policy, large-scale studies assessing important outcomes, and directly comparing vaccine types are urgently required. The degree of scrutiny needed to identify all global cases of potential harms is beyond the resources of this review.

This review includes trials funded by industry. 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 favourable 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 the light of this finding.

I'd be interested to know if they provide the same warnings for other flu studies for other age groups or demographics ...

[Eligracey]

Originally Posted by MamaMunchkin 

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From the second link - click on Abstract (click to read) at the bottom ...

http://summaries.cochrane.org/CD004879/vaccines-for-preventing-influenza-in-healthy-children

 

Authors' conclusions: 

Influenza vaccines are efficacious in preventing cases of influenza in children older than two years of age, but little evidence is available for children younger than two years of age. There was a difference between vaccine efficacy and effectiveness, partly due to differing datasets, settings and viral circulation patterns. No safety comparisons could be carried out, emphasising the need for standardisation of methods and presentation of vaccine safety data in future studies. In specific cases, influenza vaccines were associated with serious harms such as narcolepsy and febrile convulsions. It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months of age in the USA, Canada, parts of Europe and Australia. If immunisation in children is to be recommended as a public health policy, large-scale studies assessing important outcomes, and directly comparing vaccine types are urgently required. The degree of scrutiny needed to identify all global cases of potential harms is beyond the resources of this review.
 

Well, if they conclude that the flu vaccine is ineffective for kids under 2 based on only one study, I'm not really convinced by that either way.  Rather than concluding that the flu vax is ineffective for kids under 2, I think you'd have to conclude that we are currently unaware of whether the flu vax is effective for kids under 2.

[Rrrrrachel]

Sure, thy bring up a lot of issues with the flu vaccine, and in particular with public health policy. Absolutely. There's lots of good stuff to talk about in there. But you know what they never say? That the flu vaccine is ineffective.

[kathymuggle]

Originally Posted by Eligracey 

Well, if they conclude that the flu vaccine is ineffective for kids under 2 based on only one study, I'm not really convinced by that either way.  Rather than concluding that the flu vax is ineffective for kids under 2, I think you'd have to conclude that we are currently unaware of whether the flu vax is effective for kids under 2.

That is not what it said.

it said, and you bolded:

 It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months of age in the USA, Canada, parts of Europe and Australia.

The above quote does not talk about effectiveness.  It simply mentions that they find it surprising that the inactivated flu vax is given to children under two on the strength of only one study. 

It is the responsibility of the vaccine community to prove a particular vaccine is safe and effective before dispersing it to a community.  If there is only one study of inactivated flu virus in kids under 2, it seems they failed to do that.

[kathymuggle]

Originally Posted by Rrrrrachel 

Sure, thy bring up a lot of issues with the flu vaccine, and in particular with public health policy. Absolutely. There's lots of good stuff to talk about in there. But you know what they never say? That the flu vaccine is ineffective.

To say the flu vaccine is ineffective across the board they would probably need to find zero or very close to zero levels of effectiveness.  

From the report on adults:

"In the relatively uncommon circumstance of vaccine matching the viral circulating strain and high circulation, 4% of unvaccinated people versus 1% of vaccinated people developed influenza symptoms (risk difference (RD) 3%, 95% confidence interval (CI) 2% to 5%). The corresponding figures for poor vaccine matching were 2% and 1% (RD 1, 95% CI 0% to 3%)"

It is not good enough for me - but it is not "nothing."

Flu vaccines  do not seem to affect hospital admissions at all, and the summary I found showed no affect of work loss, while mama munchkins showed mild effect on work loss (odd - because both of us were quoting the same study - her the authors conclusion, me the plain language summary…)

If people are saying "not effective at all in healthy adults" I suppose it is fair to call them on it.  If people are saying "highly problematic, not as effective as we are lead to believe, not overly useful in certain populations….."  that would be a correct statement.  

Edited by kathymuggle - 12/2/12 at 6:17am

[MamaMunchkin]

The issue is not just whether the flu vax is effective/not, but also the nature of the studies/data the conclusion is based on ...

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 the light of this finding.

It'd be great if they share this evidence with the public ... anyone has sources/links ...?

Edited by MamaMunchkin - 12/2/12 at 7:26am

[Rrrrrachel]

Actually, mama, the issue is whether it's effective or not. If you'd like to discuss something else maybe start another thread. This one is to address the specific claim that the cochrane review said the flu shot is not effective.

[MamaMunchkin]

nm ...

Edited by MamaMunchkin - 12/2/12 at 8:29am

[kathymuggle]

Originally Posted by MamaMunchkin 

I'm very interested to know whether the flu vax is effective or not, however Cochrane provides a warning on how to interpret this finding.

I do not have time to do it right now - but it might be interesting to compare whether Cochrane usually provides a warning like the one they did for flu studies:

"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."

If they don't, it might mean they think flu studies are somehow more prone to widespread manipulation than other vaccines.

[MamaMunchkin]

Kathy, we x-posted.  I edited the post you quoted above ... but am still interested ... anyway ... 

Edited by MamaMunchkin - 12/2/12 at 9:00am