Effectiveness of flu vaccines

[mhatrw]

http://www2.cochrane.org/reviews/en/ab004876.html">Effectiveness in seniors

Vaccines for preventing seasonal influenza and its complications in people aged 65 or older

Influenza vaccination of elderly individuals is recommended worldwide as people aged 65 and older are at a higher risk of complications, hospitalisations and deaths from influenza. This review looked at evidence from experimental and non-experimental studies carried out over 40 years of influenza vaccination. We included 75 studies. These were grouped first according to study design and then the setting (community or long-term care facilities). The results are mostly based on non-experimental (observational) studies, which are at greater risk of bias, as not many good quality trials were available. Trivalent inactivated vaccines are the most commonly used influenza vaccines.Due to the poor quality of the available evidence, any conclusions regarding the effects of influenza vaccines for people aged 65 years or older cannot be drawn. The public health safety profile of the vaccines appears to be acceptable.

http://www2.cochrane.org/reviews/en/ab004876.html">Effectiveness in healthy children

Vaccines for preventing influenza in healthy children

...

The review authors found that in children aged from two years, nasal spray vaccines made from weakened influenza viruses were better at preventing illness caused by the influenza virus (82% of illnesses were prevented) than injected vaccines made from the killed virus (59%). Neither type was particularly good at preventing 'flu-like illness' caused by other types of viruses (33% and 36% respectively). In children under the age of two, the efficacy of inactivated vaccine was similar to placebo. It was not possible to analyse the safety of vaccines from the studies due to the lack of standardisation in the information given but very little information was found on the safety of inactivated vaccines, the most commonly used vaccine, in young children.

http://www2.cochrane.org/reviews/en/ab001269.html">Effectiveness in healthy adults

Vaccines to prevent influenza in healthy adults

...

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.

http://www2.cochrane.org/reviews/en/ab005187.html">Effectiveness in healthcare workers who work with the elderly

There are no accurate data on rates of laboratory-proven influenza in healthcare workers. The three studies in the first publication of this review and the two new studies we identified in this update are all at high risk of bias.

The studies found that vaccinating healthcare workers who look after the elderly in long-term care facilities did not show any effect on the specific outcomes of interest, namely laboratory-proven influenza, pneumonia or deaths from pneumonia. ...

Healthcare workers have lower rates of influenza vaccination than the elderly and surveys show that healthcare workers who do not get vaccinated do not perceive themselves at risk, doubt the efficacy of influenza vaccine, have concerns about side effects, and some do not perceive their patients to be at risk. ...

We conclude that there is no evidence that only vaccinating healthcare workers prevents laboratory-proven influenza, pneumonia, and death from pneumonia in elderly residents in long-term care facilities. ...

http://www.cochrane.org/podcasts/issues-1-3-january-march-2010/two-updated-reviews-influenza-vaccines">Audio summary of effectiveness of influenza vaccines on the elderly and healthcare workers who work with the elderly

http://onlinelibrary.wiley.com/o/cochrane/clsysrev/articles/CD004876/frame.html">Full Text of Updated Study on Vaccines for Preventing Influenza in the Elderly

Authors' conclusions

The available evidence is of poor quality and provides no guidance regarding the safety, efficacy or effectiveness of influenza vaccines for people aged 65 years or older. To resolve the uncertainty, an adequately powered publicly-funded randomised, placebo-controlled trial run over several seasons should be undertaken.

http://www.cochrane.org/podcasts/influenza/summary-cochrane-reviews-influenza">Audio summary of the overall comparable effectiveness of all influenza preventatives and interventions

[damntexdem]

1. I still feel better, and safer, after I've had my shot.

Of course, I'm "only" 64.

[mhatrw]

3. I'm really not here to dissuade you from doing so.

Better evidence may show that flu vaccinations actually are effective for your age group in the future.

Until then, there is always the potential of a placebo effect to tide us over.

I still think that everyone should at least try to request single dose flu vaccinations (the ones without thimerosal in them) when and if possible. I am not claiming a link between thimerosal and autism. I just find it strange that mercury has been removed from almost every vaccine except for the one that everyone is recommended to get every year, even though it doesn't work very well.

[SheilaT]

2. I've actually seen similar studies

going back maybe 20 years. They just don't get the kind of coverage that the "OMG! WE'RE ALL GOING TO DIE IF WE DON'T ALL GET FLU SHOTS" gets.

I'm 62, never get flu shots, got what presumably was flu several times in my childhood or young adulthood. Probably the last time I got anything resembling flu was more than 30 years ago.

The other truth that people hate to face is that if you get flu and recover -- which the very vast majority of people do -- you now have a strong immunity to future flu outbreaks. The main reason so few people over age 50 came down with the flu in the 1918 epidemic was that about a half century earlier there was a flu epedimic of a similar type of virus, and the older people had survived that.

[mhatrw]

4. Just to be clear here, I was not citing singular studies.

Each and every article presented above represents (at least a very good attempt at) a comprehensive review of every available study to date on each subject reviewed.

[LeftishBrit]

7. Getting the flu and recovering protects against related strains of flu, but not all

I believe it's also been suggested that older people now may not be catching the swine flu in huge numbers because there was an epidemic of a somewhat related flu strain in the 1950s. But many middle aged and younger people came down with the flu in 1968, and/or in 1989 (there was a big flu epidemic in the UK then; I'm not sure if it affected the USA as much); and neither of these has resulted in immunity to the swine flu.

[SheilaT]

8. The 1968 flu epidemic

known here as the Hong Kong flu, definitely hit the U.S. It was a type A flu, same as the swine flu. I know I didn't get anything that year, but I think I got the Asian flu, 1957, an even more virulent version of a type A.

Remember the Swine Flu epidemic of 1976 and the millions who died? Oh, wait, except for the unfortunate soldier in Ft. Dix who managed to die, no one else got it.

I am truly bothered by the flu scare hype that is constantly out there. Ever since 1976 it has been totally out of proportion to the actual risk. Last year there was near-hysteria over the flu, which turned out to be an unusually mild version. Meanwhile, because of the scare tactics, hospital emergency rooms were overwhelmed by people who often weren't really sick at all. Worse yet, in the hospital where I work, entire families would crowd a waiting room when maybe one member exhibited flu-like symptoms. THAT'S a very efficient way to spread any kind of illness, not just flu.

[LeftishBrit]

9. In the UK during the 2009 swine flu...

people were urged *not* to immediately go to the doctor with flu symptoms, but to stay at home, and ring either the surgery or a particular NHS 'flu advice' number in the first instance. Then decisions could be made on the basis of their symptoms as to what was needed (e.g. get a family member or neighbour to collect Tamiflu for them; just rest in bed and take lots of fluids; go to the hospital only in severe cases). I think that this policy contributed both to reducing spread of the swine flu as such, and also other illnesses.

[SheilaT]

11. How sensible!

I kind of think people here were advised the same thing, but a lot of them never listen to or read whatever source would have been putting out that information.

Alas, too many lack what is erroneously called common sense.

[trotsky]

5. From the CDC

http://www.cdc.gov/flu/professionals/vaccination/effectivenessqa.htm

Healthy Children

A randomized, double-blind, placebo-controlled trial among 1,602 healthy children initially aged 15--71 months assessed the efficacy of trivalent LAIV against culture-confirmed influenza during two seasons (Belshe et al., N Engl J Med 1998;338:1405—12. Belshe et al, J Pediatr 2000;136:168--75). In season one, when vaccine and circulating virus strains were well-matched, efficacy in preventing confirmed illness from influenza was 93% for participants who received 2 doses of LAIV. In season two, when the A (H3N2) component was not well-matched between vaccine and circulating virus strains, efficacy was 86% overall.

...

Healthy Adults

A randomized, double-blind, placebo-controlled trial among 4,561 healthy working adults aged 18--64 years assessed multiple endpoints, including reductions in self-reported respiratory tract illness without laboratory confirmation, absenteeism, healthcare visits, and medication use during peak and total influenza outbreak periods (Nichol et al., JAMA 1999;282:137--44). The study was conducted during the 1997--98 influenza season, when the vaccine and circulating A (H3N2) strains were not well-matched. Vaccination was associated with reductions in severe febrile illnesses of 19%, and febrile upper respiratory tract illnesses of 24%.

Vaccination was also associated with fewer days of illness, fewer days of work lost, fewer days with healthcare provider visits, and reduced use of prescription antibiotics and over-the-counter medications. Among a subset of 3,637 healthy adults aged 18--49 years, LAIV recipients (n = 2,411) had 26% fewer febrile upper-respiratory illness episodes; 27% fewer lost work days as a result of febrile upper respiratory illness; and 18%--37% fewer days of healthcare provider visits caused by febrile illness, compared with placebo recipients (n = 1,226). Days of antibiotic use were reduced by 41%--45% in this age subset.

These and the Canadian study of Mennonites confirm that while the immune system of the elderly isn't all that well stimulated by the flu vaccine, the rest of us getting vaccinated is indeed effective - both for ourselves and our elders. This is a liberal principle - sharing a tiny risk to gain and share a huge reward. It is lost on the anti-vax movement, which is driven by selfishness, ignorance, and limited thinking.

[mhatrw]

10. The CDC is cherry picking just the studies that show what they wish to show,

Flumist actually works pretty well in children over 2, but it was shown to have no effectiveness in adults over 50. Note that 2 of the three studies the CDC cited above are about Flumist. All of these studies are well-known to the authors of the summaries cited above.

Vaccination was also associated with fewer days of illness, fewer days of work lost, fewer days with healthcare provider visits, and reduced use of prescription antibiotics and over-the-counter medications. Among a subset of 3,637 healthy adults aged 18--49 years, LAIV recipients (n = 2,411) had 26% fewer febrile upper-respiratory illness episodes; 27% fewer lost work days as a result of febrile upper respiratory illness; and 18%--37% fewer days of healthcare provider visits caused by febrile illness, compared with placebo recipients (n = 1,226). Days of antibiotic use were reduced by 41%--45% in this age subset.

Explain to me how getting Flumist resulted in a 41% reduction of antibiotic use. Doesn't this damn the supposed "randomization" of this experiment?



A larger version of this chart can be accessed here.

Why is the strongest effect of Flumist in all cases to reduce the use of antibiotics?

Here's a graph from the above study comparing comparing the percentages reporting symptoms within 7 days of receiving either the vaccine or a placebo.



Here is a graph showing the demographic breakdown of the placebo vs. vaccinated group



Note that the placebo group had 13.7% more blacks and 15.0% more participants who never attended college than did the vaccinated group. Could these differences have anything to do with the modest reductions in illness shown by the vaccinated group?

the Canadian study of Mennonites

You mean the Hutterite study that used a Hepatitis A vaccination as its placebo control?

This is a liberal principle - sharing a tiny risk to gain and share a huge reward. It is lost on the anti-vax movement, which is driven by selfishness, ignorance, and limited thinking.

What's lost on the Big Pharma and the CDC is that if you want to ask people to take a tiny risk for the health of others, you should actually do everything possible to make that risk as tiny as possible. This includes removing all thimerosal from all flu vaccinations. Why is this too much to ask?

[trotsky]

14. They're not cherry-picking, YOU are.

The antibiotic use stat does nothing to compromise the randomness. I tell you what - ANY and ALL questions that you have because you don't understand, can be submitted to the study authors. Their names and institutions are clearly listed. I challenge you to do exactly this and get your concerns addressed. I double dog dare ya. Will you take me up on the challenge?

This includes removing all thimerosal from all flu vaccinations. Why is this too much to ask?

Because thimerosal in vaccines has never been shown to cause any harm. It is a highly effective preservative for multi-dose vaccines, which helps keep the cost down and in turn helps make it available to more people. Why does everything have to be a conspiracy for you?

[mhatrw]

15. Why don't YOU ask the CDC to respond to the Cochrane Reviews in the OP?

Why don't you explain to me exactly how getting vaccinated with a live, attenuated flu virus cut down on the use of anti-bacterial antibiotics by 41%?

Why don't you show us the studies that demonstrate thimerosal's supposedly superior effectiveness as a preservative?

Basically your argument for using thimerosal in flu vaccines comes down to vaccine manufacturers and distributors wanting to pinch a few pennies at the possible expense of the health and well-being of hundreds of millions of Americans (in order to elicit some sort of unproven herd immunity to protect others in the community from a threat that 99% of healthy individuals can fully recover from in less than a week).

The difference between the cost to the manufacturers of thimerosal-free single dose vaccines and thimerosal laden multidose vaccines is far less than $1.00 a dose. SP, for example, sells Fluzone thimerosal-free single dose vials for about $11.00 a dose as compared to 10 dose thimerosal-laden vials for about $10.00 a dose. Besides containing mercury, mulitdose vials also offer a http://www.google.com/url?sa=t&source=web&cd=15&ved=0CDYQFjAEOAo&url=http%3A%2F%2Fwww.infectioncontrolresource.org%2FPast_Issues%2FIC11.pdf&rct=j&q=influenza%20vaccination%20(pricing%20OR%20cost)%20single%20dose%20multidose&ei=hodATY7VHpTmsQPmgrXkCA&usg=AFQjCNFRrnyDPNyEZn118lnVgPDEi3cNQw&cad=rja">far greater risk of both bacterial and viral cross-contamination, all just to save about a buck per individual vaccinated. Does this really strike you as good public policy? Is the health and safety of our vaccinated population really worth so little to you and the CDC? If so, how can we trust either you or the CDC to make sound health care recommendations for the US populace?

If the benefits to one's personal health are this small, then every effort should be expended to make eliminate all potential health risks. What about this primary tenet of medical decision making is so difficult for you to comprehend?

[trotsky]

16. Because you've proven your knowledge on this subject is incomplete at best.

You're the one who needs to be educated. You're the one who doesn't understand even basic chemistry and how the properties of an element are not the same as the properties of a compound.

You've lost again, because the facts are simply not on your side. I'm so sorry.

[mhatrw]

17. Ethyl mercury, methyl mercury and elemental mercury are ALL highly toxic.

You know it, I know it, and everybody else who knows anything about anything knows it. In the case of this one element and these two compounds of this one element, no real distinction needs to be made because all three are highly toxic to all mammals.

http://www.springerlink.com/content/v0203116418023h8

Neurotoxicity and renotoxicity were compared in rats given by gastric gavage five daily doses of 8.0 mg Hg/kg methyl- or ethylmercuric chloride or 9.6 mg Hg/kg ethylmercuric chloride. Three or 10 days after the last treatment day rats treated with either 8.0 or 9.6 mg Hg/kg ethylmercury had higher total or organic mercury concentrations in blood and lower concentrations in kidneys and brain than methylmercury-treated rats. In each of these tissues the inorganic mercury concentration was higher after ethyl than after methylmercury.

Weight loss relative to the expected body weight and renal damage was higher in ethylmercury-treated rats than in rats given equimolar doses of methylmercury. These effects became more severe when the dose of ethylmercury was increased by 20%. Thus in renotoxicity the renal concentration of inorganic mercury seems to be more important than the concentration of organic or total mercury. In methylmercury-treated rats damage and inorganic mercury deposits were restricted to the P2 region of the proximal tubules, while in ethylmercury-treated rats the distribution of mercury and damage was more widespread.

There was little difference in the neurotoxicities of methylmercury and ethylmercury when effects on the dorsal root ganglia or coordination disorders were compared. Based on both criteria, an equimolar dose of ethylmercury was less neurotoxic than methylmercury, but a 20% increase in the dose of ethylmercury was enough to raise the sum of coordination disorder scores slightly and ganglion damage significantly above those in methylmercury-treated rats.

[trotsky]

18. What you "know" ain't always so.

But Dunning Kruger is proven with you, that's for sure.

[mhatrw]

19. It's great that the CDC has seen fit to deliver our flu vaccinations

to us through thimerosal laden multi-use vials that the CDC itself recommends against strongly.

Could such poor decision making possibly be explained by the Lobbying-Sewer effect?

[trotsky]

20. Excuse me - "thimerosal laden"? I mean, really?

That's right out of the Gingrich playbook. Seriously, can't you do better than that?

[mhatrw]

21. Is that really all you have? That I overstated my case?

I want to hear your justification for using multi-dose vaccines that contain thimerosal and can easily spread both viral and bacterial infection when single-dose vials would cost only a dollar more and the net cost of single-dose pre-filled syringes (when the labors costs of the administration of vaccines are also considered) would actually save money compared to using multi-dose vials.

Is it really so important for you to force my child to get her ethyl mercury along with her recommended flu vaccinations that you want us all to pay extra for it?

[trotsky]

22. No, it's impossible for you to overstate your case.

Because you don't have one. All you have are wild conspiracy charges that you fling around without the slightest evidence whatsoever. You've demonstrated, beyond the shadow of a doubt, that you don't even understand the most basic properties of chemistry or physiology. How on earth do you expect people to take you seriously?

Is it really so important for you to force my child to get her ethyl mercury along with her recommended flu vaccinations that you want us all to pay extra for it?

Is it really so important for you to attack me personally, as if I were a vaccine producer or someone who profited from the ZOMG POISONING OF INNOCENT CHILDREN?

I am only interested in facts, and the facts are that thimerosal is a safe, effective vaccine preservative, with absolutely no evidence implicating it in any health problems whatsoever EXCEPT for allergic reactions at the site of injection. That's it. That's all we have evidence for. And even though it was removed from ALL standard childhood vaccines over 10 years ago, and there has been NO reduction in autism AT ALL, you obsess over it, bring out your unfounded conspiracy charges, your personal attacks, your questioning of motives, and ATTACK, ATTACK, ATTACK relentlessly.

You have no facts on your side. You have no evidence on your side. You have only fear, misinformation, and unfounded conspiracies.

[HuckleB]

23. +1,000,000,000,000!!!

[mhatrw]

24. Please explain why it is a bad idea for us to pay about $1 more per flu vaccine dose

to avoid all potential multi-dose cross-contamination and all thimerosal completely.

Let's hear it. Why is it not worth paying just a dollar more per dose to rid our flu vaccines of both ethyl mercury and the very real threat of cross-contamination?

[trotsky]

25. I've already told you countless times.

But you ignore what you don't want to hear. So why should I repeat myself again?

[mhatrw]

26. LOL

[trotsky]

27. Go look in the other thread where you recently asked this.

I'm not going to post the same answer 400 times just to please you.

[mhatrw]

28. Found it.

[LeftishBrit]

6. What really needs to be done ...

is to develop vaccines that will protect against many strains of the flu, not just those predicted for a particular season. At present, the flu vaccine is only as good as the predictions for the season: very good sometimes, not so good at other times.

I believe that there is work going on to develop more universal flu vaccines, which might also mean that one vaccine might work for several years, and people would not need to get it every year.

[mhatrw]

13. Yes, and they need to get the thimerosal out of recommended flu vaccinations.

If you are going to recommend that everyone get these largely ineffective shots annually, you need to make these shots as safe as possible.

I realize from my previous experiences on the is forum that my sentiments on this subject clearly brand me as a wild-eyed radical anti-vax nutcase, but I'm really not sure how.

[hedgehog]

12. I note one of the phrases that you put into bold face:

"surveys show that health care workers who do not get vaccinated do not perceive themselves at risk, doubt the efficacy of influenza vaccine, have concerns about side effects"

This is not a statement that health care workers are not at risk, that the vaccine is not effective, or that people should be concerned about side effects.

This is a statement that the people surveyed think all these things are true.

The author's conclusions: "The available evidence is of poor quality and provides no guidance regarding the safety, efficacy or effectiveness of influenza vaccines for people aged 65 years or older." are old new. Immune systems in the elderly are not as efficient as in younger people. As a result, for many, the flu vaccine is ineffective. In recent years, recommendations have been that the best way to protect the elderly is to vaccinate their contacts, so the elderly are not exposed to the virus. IIRC, a Japanese study showed that the most effective way to protect the elderly was to protect school children, thereby limiting flu outbreaks.