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Flu Vaccine much less effective for those over 70

 

A very interesting article.  Problem with population studies concerning elderly getting flu vaccine was that the major confounding variable, frailty was not controlled for.  Frail elder are less likely to get vaccinated and more likely to die from the flu—they are also less likely to go to the doctor. Thus all the past studies had over represented the frail unvaccinated group.  Those who got vaccinated were less likely to die because they were healthier—not because of the vaccine.  Moreover, a study which used incidents of cancer and heart disease as a marker for frail also failed because those who weren’t frail were more likely to go to the doctor and thus be recorded as having these conditions.   

 

Three studies set the record straight.  A double blind study was done in 1994 which showed little benefit for the vaccine in preventing deaths.  Finally, a recent study based on frailty markers of lung function, the ability to bathe and dress, and use of certain medication, this study found that vaccination had little effect on older people’s risk for pneumonia—the most dangerous complication of influenza.  The reason for the failure of the vaccine was found in another recent study where the elderly need 4 times the amount of antigens given in a standard dose to produce the immune response as a healthy adult under 40. 

 

Doubts Grow Over Flu Vaccine in Elderly

September 2, 2008, by Brenda Goodman, New York Times

 The influenza vaccine, which has been strongly recommended for people over 65 for more than four decades, is losing its reputation as an effective way to ward off the virus in the elderly.      A growing number of immunologists and epidemiologists say the vaccine probably does not work very well for people over 70, the group that accounts for three-fourths of all flu deaths.      The latest blow was a study in The Lancet last month that called into question much of the statistical evidence for the vaccine's effectiveness.

    The authors said previous studies had measured the wrong thing: not any actual protection against the flu virus but a fundamental difference between the kinds of people who get vaccines and those who do not.      This contention is far from universally accepted. And even skeptics say that until more effective measures are found, older people should continue to be vaccinated, because some protection against the flu is better than none.

    Still, the Lancet article has reignited a longstanding debate over claims that the vaccine prevents thousands of hospitalizations and deaths in older people. "The whole notion of who needs the vaccine and why is changing before our eyes," said Peter Doshi, a doctoral candidate at M.I.T. who published a paper on the historical impact of influenza in May in The American Journal of Public Health.       The Lancet paper, by Michael L. Jackson and colleagues at the Group Health Center for Health Studies in Seattle, was based on an analysis of medical charts of thousands of elderly members of an H.M.O.    The study found that people who were healthy and conscientious about staying well were the most likely to get an annual flu shot. Those who are frail may have trouble bathing or dressing on their own and are less likely to get to their doctor's office or a clinic to receive the vaccine. They are also more likely to be closer to death.

    Dr. David K. Shay of the Centers for Disease Control and Prevention, a co-author of a commentary that accompanied Dr. Jackson's study, agreed that these measures of health and frailty "were not incorporated into early estimations of the vaccine's effectiveness" and could well have skewed the findings.

    Not everyone is sold on the significance of the Lancet study. "I think this is another study that provides interesting findings and raises questions," said Dr. Kristin Nichol, chief of medicine at the Veterans Affairs hospital in Minneapolis. "I don't think we know yet what the final word is on influenza vaccinations in the elderly. “     "I really feel, and I feel very strongly about this, that the public health message should be that vaccines are effective," she continued. "I don't think that science is necessarily best hashed out in the media."

    Dozens of studies since 1960 have supported the view that the vaccine is a powerful protector of the elderly, cutting their risk of dying in winter from any cause by almost 50 percent and reducing the risk of hospitalization by nearly 30 percent.    Those findings came from observational studies, in which scientists make inferences about the effect of a treatment on a population by comparing what happens to a group that has the treatment with what happens to an apparently similar group that does not.   

 There has been only one large study that compared the flu vaccine with a placebo for two random groups of older people in which neither the patients nor the scientists knew which group was receiving which injection. It came to a different conclusion from the observational studies. Conducted by Dutch researchers and published in 1994 in The Journal of the American Medical Association, it found that in those 60 to 69, the vaccine prevented influenza about 57 percent of the time. In those over 70, the vaccine prevented the flu just 23 percent of the time, though the estimate is imprecise because the study was not designed to look at this age group.

    Because of this failure to rely upon the placebo-controlled trials, which are considered the gold standard in medical evidence, health policy was based flawed studies.  "I think the evidence base we have leaned on is not valid," said Lone Simonsen, an epidemiologist and visiting professor at the George Washington University School of Public Health and Health Services in Washington who was not connected with the Lancet study.

    In 2005, Dr. Simonsen, who was then at the National Institute of Allergy and Infectious Diseases in Bethesda, Md., published a paper in The Archives of Internal Medicine that found something odd: even though the percentage of older people who got an annual flu shot more than tripled from 1980 to 2001, there was no corresponding drop in the death rate.   That paper included one of the first estimates of how many deaths are actually caused by the flu - a number hard to pin down because doctors seldom confirm flu in their patients with lab tests. Using a statistical model and the best available data, Dr. Simonsen found that influenza probably causes just 5 to 10 percent of all winter deaths in the elderly. But earlier studies had found that the flu vaccine cut an elderly person's risk of dying by 50 percent.

    "You don't have to do a whole lot of math to realize that doesn't add up," said Dr. Lisa A. Jackson of the Group Health Center for Health Studies in Seattle, who has also studied the effectiveness of the flu vaccine in the elderly.

    Dr. Jackson at first tried to tease out underlying differences between vaccinated and unvaccinated elderly people by using medical codes - a numerical shorthand that doctors use to classify and record what is wrong with their patients. She and other researchers reasoned that patients with codes for cancer or heart disease, for example, might be very sick, thus skewing the results. When they adjusted for those codes, however, the differences between the vaccinated and unvaccinated groups became even more pronounced. The vaccine looked even more protective.

    It was Michael L. Jackson's thesis project, at the University of Washington, that revealed the flaw in using the codes to differentiate patients.   For the project, Mr. Jackson (no relation to Lisa Jackson) and three other researchers spent almost three years reading medical charts and examining X-rays. They discovered that health-conscious people were more likely to get medical codes for things like heart disease and cancer simply because they went to the doctor more often. But when Mr. Jackson adjusted for measures of frailty - things like lung function, whether people needed help bathing or dressing, and what kinds of medications they took - he found that vaccination had little effect on older people's risk for pneumonia, the most dangerous complication of the flu.

    That finding has a biological basis. Vaccines work by priming the immune system to recognize and respond to incoming threats. Because the immune system slows down with age, older adults do not respond as well to vaccines as younger adults.   A recent study by Dr. Wilbur H. Chen and colleagues at the Center for Vaccine Development at the University of Maryland School of Medicine found that elderly participants needed four times the amount of antigens given in a standard dose of the flu vaccine to have the same kind of immune response as healthy adults under 40. They presented their findings in May at the Annual Conference on Vaccine Research in Baltimore.

    Despite these findings, Dr. Shay said the C.D.C. had no plans to change its vaccine recommendations, though he added that the agency had financed studies to look for more effective influenza vaccines for the elderly.  

    Dr. Simonsen, the epidemiologist at George Washington, said the new research made common-sense infection-control measures - like avoiding other sick people and frequent hand washing - more important than ever. Still, she added, "The vaccine is still important.  Thirty percent protection is better than zero percent."

 

 

Cochrane Library publishes the Cochrane Review, an international evidence based group often doing meta-analysis of first quality.  It is one of the very few sources for organizations that looks to the evidence, is neither run by the marketing departments of drug companies are receiving pay therefrom.  Every year they publish studies design to guide the medical community away from serious errors.  In much of the world state funds are used to make the Cochrane Review free to the people.  Only Wyoming provide such access in the U.S. 

Study: No hard evidence that flu vaccine protects the elderly

February 18, 201010:01am ET | By John Carroll

 

After a detailed analysis of 75 scientific studies, a group of researchers at the Cochrane Library has concluded that there's little hard evidence to prove that the annual flu vaccination campaign for the elderly does any good.

The vaccine won't work unless it's particularly well matched to the flu strains in circulation, say the researchers. Some of the elderly don't respond to the vaccine at all, and the most vulnerable often don't bother to get a shot. And the data on flu rates in older people is often badly skewed by ailments that have the same symptoms as flu but aren't affected by vaccine at all.

The analysis drew considerable attention in the U.K., where the government pays about 150 million pounds a year to vaccinate three quarters of the older population. Officially, the government estimates that the flu kills about 12,000 people a year in England. But the Cochrane group says there really are no good estimates available and the government figure is probably far too high.

"As the evidence is so scarce at the moment, we should be looking at other strategies to complement vaccinations," notes Tom Jefferson of the Cochrane Collaboration in Rome. "Some of these are very simple things like personal hygiene, and adequate food and water. Meanwhile, we need to undertake a high quality, publicly funded trial that runs over several seasons to try to resolve some of the uncertainties we're currently facing."

There's been widespread recognition among vaccine manufacturers that the currently available vaccines are least effective in the elderly. And there are a number of new programs underway to design a vaccine that can protect this patient population.

- here's the press release
- here's the story from The Telegraph

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From the Cochrane Library

 

 http://summaries.cochrane.org/CD004876/vaccines-for-preventing-seasonal-influenza-and-its-complications-in-people-aged-65-or-older

 

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

Jefferson T, Di Pietrantonj C, Al-Ansary LA, Ferroni E, Thorning S, Thomas RE

Published Online: February 17, 2010


 

Abstract

Background

Vaccines have been the main global weapon to minimise the impact of influenza in the elderly for the last four decades and are recommended worldwide for individuals aged 65 years or older. The primary goal of influenza vaccination in the elderly is to reduce the risk of complications among persons who are most vulnerable.

Objectives

To assess the effectiveness of vaccines in preventing influenza, influenza-like illness (ILI), hospital admissions, complications and mortality in the elderly. 
To identify and appraise comparative studies evaluating the effects of influenza vaccines in the elderly. 
To document types and frequency of adverse effects associated with influenza vaccines in the elderly.

Search methods

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register (The Cochrane Library 2009, issue 4); MEDLINE (January 1966 to October Week 1 2009); EMBASE (1974 to October 2009) and Web of Science (1974 to October 2009).

 

Selection criteria

Randomised controlled trials (RCTs), quasi-RCTs, cohort and case-control studies assessing efficacy against influenza (laboratory-confirmed cases) or effectiveness against influenza-like illness (ILI) or safety. Any influenza vaccine given independently, in any dose, preparation or time schedule, compared with placebo or with no intervention was considered.

Data collection and analysis

We grouped reports first according to the setting of the study (community or long-term care facilities) and then by level of viral circulation and vaccine matching. We further stratified by co-administration of pneumococcal polysaccharide vaccine (PPV) and by different types of influenza vaccines. We analysed the following outcomes: influenza, influenza-like illness, hospital admissions, complications and deaths.

Main results

We included 75 studies. Overall we identified 100 data sets. We identified one RCT assessing efficacy and effectiveness. Although this seemed to show an effect against influenza symptoms it was underpowered to detect any effect on complications (1348 participants). The remainder of our evidence base included non-RCTs. Due to the general low quality of non-RCTs and the likely presence of biases, {funded by and edited by the drug company} which make interpretation of these data difficult and any firm conclusions potentially misleading, we were unable to reach clear conclusions about the effects of the vaccines 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.