Flu Shots

[kellyb]

http://www.bmj.com/cgi/content/full/333/7574/912

What in the hell?

Yeah...there are a bunch of viruses that "act" just like "the flu". They've done studies on people admitted to the hospital with "influenza like illness" and it's generally only 10-20% of them that end up having actual influenza. The rest are RSV, adenoviruses, rhinoviruses, human metapneumovirus, etc.

ETA:
Here's one that found it was 28% of people with "the flu" that had actual influenza in the year with the most influenza activity over 5 years:

http://www.health.gov.au/internet/w...nt/cda-pubs-cdi-2004-cdi2802-htm-cdi2802d.htm

In the winter of 2003 Western Australia experienced its largest epidemic of influenza for at least five years, with activity peaking in August and September. The season was short resulting in very high numbers of cases during the peak weeks. Activity in country areas followed the peak of Metropolitan activity. Influenza A virus was detected in 28.3 per cent of the sentinel samples, and influenza B in less than one per cent. Both routine and sentinel detections and the overall estimates of influenza-like illnesses (ILI) seen by general practitioners at sentinel practices peaked in August and September 2003. The combination of influenza detections and an increase in ILI seemed to be the most accurate predictor of the beginning of winter influenza activity. There was a shift in age distribution for influenza A compared with 2003. Both the sentinel surveillance and routine samples demonstrated an increase of influenza in children and young adults. The majority of influenza A isolates were identified as A/Fujian/411/2002-like, a variant of the A/Moscow strain included in the vaccine. Despite this mismatch there did not seem to have been any noticeable increase in the risk of influenza infection in the vaccinated populations from the sentinel practices, nor was there a relative increase in disease among the highly vaccinated elderly population. A number of other respiratory viruses were identified as causes of influenza-like illness in the sentinel samples. Rhinoviruses and human metapneumovirus were the most common, the latter occurring mainly in adults. Commun Dis Intell 2004;28:169-174.

And as far as viruses that are the most likely to land a kid in the hospital:

http://www.medscape.com/viewarticle/468724_4

RSV A and B. We estimate that ~116 500 children are hospitalized each year in the United States because of RSV infection. This number grows to ~144 000/year if we include children seen at CHW as outpatients (mostly emergency room visits). Approximately 50% of the identified (by MPCR) common respiratory viruses in hospitalized previously healthy children were RSV A and B.

PIV-1, -2 and -3. Combined, this family of viruses causes the second largest number of pediatric hospitalizations (~65 000) for community-acquired respiratory viruses

Influenza A and B. We estimate that ~40 000 children are hospitalized each year in the United States with influenza A or B infection.

As important as it is to understand how these common respiratory viruses present in hospitalized children, it is equally important to understand that there were no clinical symptoms that could be used to diagnose which virus infected which patient in our study.

 

[Skeptic Ginger]

...


The flu vaccination provides a variable level of protection against seasonal flu in these groups, ranging from poor to good. It's just that it doesn't stop many of them being admitted to hospital or dying.

Do you ever cite any sources for your claimed facts?

Effectiveness of influenza vaccine in the community-dwelling elderly.

CONCLUSIONS: During 10 seasons, influenza vaccination was associated with significant reductions in the risk of hospitalization for pneumonia or influenza and in the risk of death among community-dwelling elderly persons. Vaccine delivery to this high-priority group should be improved. Copyright 2007 Massachusetts Medical Society.

A cohort study of the effectiveness of influenza vaccine in older people, performed using the United Kingdom general practice research database.

CONCLUSIONS: Influenza vaccination reduces the number of hospitalizations and deaths due to respiratory disease, after correction for confounding in individuals >64 years of age who had a high risk or a low risk for influenza. For elderly people, untargeted influenza vaccination is of confirmed benefit against serious outcomes.

One study found there was bias in the studies in that healthier seniors were more likely to get flu shots but a number of other studies found much less bias and concluded there was indeed lower morbidity and mortality in flu shot recipients.

 

[Skeptic Ginger]

Looking at the variation (very wide) in the sensitivity and specificity in that article's chart for signs/symptoms associated with pertussis, it tells me that no one symptom is diagnostic.

1. Posttussive nausea and vomiting - common with any cough. The repetitive nature of Whooping Cough is the cause, not the origin of the illness.
2. "Barking" cough - seen in croup, tracheitis, and sometimes just in a good old URTI.
3. cough lasting longer than 2-3 weeks: varies from person to person, infection to infection. I have seen people with a good old "cold" have the couhg for 4-6 weeks after the initial infection. Allergies and Asthma also provide a sustained cough.

TAM

Many things cause persistent cough. But just out of curiosity, in adults, how frequent have you seen posttussive vomiting? I see more healthy people than sick ones and deal with the infection control and exposure follow up of pertussis, so my experience is distorted in this case. I have seen literature citing posttussive vomiting (again in adults only) as highly specific. I wonder if the specificity cited didn't include children which in my experience often have vomiting with URIs and sometimes it presents as posttussive.

Michelle is the first adult I have heard complain of this symptom during different URI events.

BTW, there is a probable and possible case definition for pertussis that I use in dx, contact tracing and work furloughs and it does of course require more than one symptom. We try to get confirmed cultures and/or serologies in all active cases.

 

[Skeptic Ginger]

Yeah...there are a bunch of viruses that "act" just like "the flu". They've done studies on people admitted to the hospital with "influenza like illness" and it's generally only 10-20% of them that end up having actual influenza. The rest are RSV, adenoviruses, rhinoviruses, human metapneumovirus, etc....

You are confusing the fact an infectious organism is not always identified (because it doesn't always need to be to treat people) with the idea the provider is somehow diagnosing people as having influenza when they have other infections. ILI and influenza are not interchangeable diagnoses. We do know the difference.

 

[Ivor the Engineer]

The full abstracts for Skeptigirl's evidence for the effectiveness of the seasonal flu vaccine:

http://www.ncbi.nlm.nih.gov/sites/e...med.Pubmed_ResultsPanel.Pubmed_RVAbstractPlus

BACKGROUND: The effectiveness of influenza vaccination against hospitalization and death can only ethically be assessed in observational studies. A concern is that individuals who are vaccinated are healthier than individuals who are not vaccinated, potentially biasing estimates of effectiveness upward. METHODS: We conducted a historical cohort study of individuals >64 years of age, for whom there were data available in the General Practice Research Database for 1989 to 1999 in England and Wales. Rates of admissions for acute respiratory diseases and rates of death due to respiratory disease were compared over 692,819 person-years in vaccine recipients and 1,534,280 person-years in vaccine nonrecipients. RESULTS: The pooled effectiveness of vaccine against hospitalizations for acute respiratory disease was 21% (95% confidence interval [CI], 17%-26%). The rate reduction attributable to vaccination was 4.15 hospitalizations/100,000 person-weeks in the influenza season. Among vaccine recipients, no important reduction in the number of admissions to the hospital was seen outside influenza seasons. The pooled effectiveness of vaccine against deaths due to respiratory disease was 12% (95% CI, 8%-16%). A greater proportionate reduction was seen among people without medical disorders, but absolute rate reduction was higher in individuals with medical disorders, compared with individuals without such disorders (6.14 deaths due to respiratory disease/100,000 person-weeks vs. 3.12 deaths due to respiratory disease/100,000 person-weeks). Clear protection against death due to all causes was not seen. CONCLUSIONS: Influenza vaccination reduces the number of hospitalizations and deaths due to respiratory disease, after correction for confounding in individuals >64 years of age who had a high risk or a low risk for influenza. For elderly people, untargeted influenza vaccination is of confirmed benefit against serious outcomes.

http://www.ncbi.nlm.nih.gov/sites/e...ez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

BACKGROUND: Reliable estimates of the effectiveness of influenza vaccine among persons 65 years of age and older are important for informed vaccination policies and programs. Short-term studies may provide misleading pictures of long-term benefits, and residual confounding may have biased past results. This study examined the effectiveness of influenza vaccine in seniors over the long term while addressing potential bias and residual confounding in the results. METHODS: Data were pooled from 18 cohorts of community-dwelling elderly members of one U.S. health maintenance organization (HMO) for 1990-1991 through 1999-2000 and of two other HMOs for 1996-1997 through 1999-2000. Logistic regression was used to estimate the effectiveness of the vaccine for the prevention of hospitalization for pneumonia or influenza and death after adjustment for important covariates. Additional analyses explored for evidence of bias and the potential effect of residual confounding. RESULTS: There were 713,872 person-seasons of observation. Most high-risk medical conditions that were measured were more prevalent among vaccinated than among unvaccinated persons. Vaccination was associated with a 27% reduction in the risk of hospitalization for pneumonia or influenza (adjusted odds ratio, 0.73; 95% confidence interval [CI], 0.68 to 0.77) and a 48% reduction in the risk of death (adjusted odds ratio, 0.52; 95% CI, 0.50 to 0.55). Estimates were generally stable across age and risk subgroups. In the sensitivity analyses, we modeled the effect of a hypothetical unmeasured confounder that would have caused overestimation of vaccine effectiveness in the main analysis; vaccination was still associated with statistically significant--though lower--reductions in the risks of both hospitalization and death. CONCLUSIONS: During 10 seasons, influenza vaccination was associated with significant reductions in the risk of hospitalization for pneumonia or influenza and in the risk of death among community-dwelling elderly persons. Vaccine delivery to this high-priority group should be improved. Copyright 2007 Massachusetts Medical Society.

So both studies confirm exactly what I said in my previous post, which was that the flu shot varies in effectiveness from poor to good and doesn't stop many people being admitted to hospital or dying. This study gives some idea of what is going on in the second study, which appears to show a significant reduction in risk of death:

BACKGROUND: Numerous observational studies have reported that seniors who receive influenza vaccine are at substantially lower risk of death and hospitalization during the influenza season than unvaccinated seniors. These estimates could be influenced by differences in underlying health status between the vaccinated and unvaccinated groups. Since a protective effect of vaccination should be specific to influenza season, evaluation of non-influenza periods could indicate the possible contribution of bias to the estimates observed during influenza season. METHODS: We evaluated a cohort of 72,527 persons 65 years of age and older followed during an 8 year period and assessed the risk of death from any cause, or hospitalization for pneumonia or influenza, in relation to influenza vaccination, in periods before, during, and after influenza seasons. Secondary models adjusted for covariates defined primarily by diagnosis codes assigned to medical encounters. RESULTS: The relative risk of death for vaccinated persons compared with unvaccinated persons was 0.39 [95% confidence interval (95% CI), 0.33-0.47] before influenza season, 0.56 (0.52-0.61) during influenza season, and 0.74 (0.67-0.80) after influenza season. The relative risk of pneumonia hospitalization was 0.72 (0.59-0.89) before, 0.82 (0.75-0.89) during, and 0.95 (0.85-1.07) after influenza season. Adjustment for diagnosis code variables resulted in estimates that were further from the null, in all time periods. CONCLUSIONS: The reductions in risk before influenza season indicate preferential receipt of vaccine by relatively healthy seniors. Adjustment for diagnosis code variables did not control for this bias. In this study, the magnitude of the bias demonstrated by the associations before the influenza season was sufficient to account entirely for the associations observed during influenza season.

 

[Professor Yaffle]

Many things cause persistent cough. But just out of curiosity, in adults, how frequent have you seen posttussive vomiting? I see more healthy people than sick ones and deal with the infection control and exposure follow up of pertussis, so my experience is distorted in this case. I have seen literature citing posttussive vomiting (again in adults only) as highly specific. I wonder if the specificity cited didn't include children which in my experience often have vomiting with URIs and sometimes it presents as posttussive.

Michelle is the first adult I have heard complain of this symptom during different URI events.

BTW, there is a probable and possible case definition for pertussis that I use in dx, contact tracing and work furloughs and it does of course require more than one symptom. We try to get confirmed cultures and/or serologies in all active cases.

As I said I often vomit from coughing ifI have a really bad cold that goes to my chest, or if I am having an asthma attack due to animal allergy. I do have a very strong gag reflex though and just brushing my teeth has made me sick occasionally. Even holding a pencil between my teeth for too long makes me gag.

 

[Rolfe]

I've had an annoying tickly cough for, I dunno, about five years. Seems to be going away gradually. When it was more severe than it is at present I had post-tussive vomiting fairly frequently. Even now, I still have it very occasionally. I don't have a diagnosis on it, it might be an allergy I suppose, but it sure as hell isn't whooping cough (I had that when I was eight, and I know the difference!).

Rolfe.

 

[Hardenbergh]

I've only had one flu shot (against my better judgment) in my entire life. I rarely get the flu but the one time I had a flu shot, I had a mild case of the flu very shortly after getting the vaccine.

My mother had one flu shot many years ago and in her own words, "I was sicker than a dog." She never allowed her doctor to talk her into getting another one. She's almost 76 years old and she's standing her ground.

 

[Dymanic]

I've only had one flu shot (against my better judgment) in my entire life. I rarely get the flu but the one time I had a flu shot, I had a mild case of the flu very shortly after getting the vaccine.

My mother had one flu shot many years ago and in her own words, "I was sicker than a dog." She never allowed her doctor to talk her into getting another one. She's almost 76 years old and she's standing her ground.

Do you feel that you have a good understanding of why it is that anecdotal evidence tends to be regarded by scientists as being of such questionable value?

 

[Rolfe]

My mother had very severe flu about 10 years ago, which progressed to bronchitis. She was very ill indeed. Ever since then she had made a point of getting a flu vaccination every year, and has never had flu since then. She has never felt the slightest bit unwell after any of the vaccinations, and pooh-poohs the idea that the vaccination might cause illness.

I had the vaccination a few weeks ago (as described in real time earlier in this thread I think), and observed no ill effects.

Are my anecdotes as good as your anecdotes?

Rolfe.

 

[Hardenbergh]

Do you feel that you have a good understanding of why it is that anecdotal evidence tends to be regarded by scientists as being of such questionable value?

It is my sincere belief that frequent handwashing equals or surpasses the benefits of a flu shot. I very rarely get a cold or the flu. Of course, some people have a stronger immune system than others.

 

[Dymanic]

It is my sincere belief that frequent handwashing equals or surpasses the benefits of a flu shot.

Being a cautious and attentive driver almost certainly reduces one's chances of being injured in an automobile accident too, but this does not negate the benefits of seatbelts and airbags.

Did you understand my question?

 

[Hardenbergh]

Being a cautious and attentive driver almost certainly reduces one's chances of being injured in an automobile accident too, but this does not negate the benefits of seatbelts and airbags.

Did you understand my question?

I guess handwashing would be of very little benefit, if we were facing an epidemic or full-blown pandemic of Swine flu. I live in a dream world.

 

[Dymanic]

I guess handwashing would be of very little benefit, if we were facing an epidemic or full-blown pandemic of Swine flu.

We face a flu epidemic every winter. During a pandemic, more people are affected, but some would be expected to avoid infection. Given the constraints on developing, manufacturing, and distributing a pandemic vaccine, precautions such as handwashing would be among the only defenses available to most people.

I live in a dream world.

It does appear that, like so many people, your decision-making process defaults to simple intuition, and you seem to be a little fuzzy on some of the basic facts as well -- but you don't have to surrender so easily; perhaps some hope remains that you can learn a more logical and evidence-based approach.

 

[Skeptic Ginger]

I've only had one flu shot (against my better judgment) in my entire life. I rarely get the flu but the one time I had a flu shot, I had a mild case of the flu very shortly after getting the vaccine.

My mother had one flu shot many years ago and in her own words, "I was sicker than a dog." She never allowed her doctor to talk her into getting another one. She's almost 76 years old and she's standing her ground.

Typical example of superstitious medicine. I'll stick with evidence based. The evidence is it works.

 

[Skeptic Ginger]

It is my sincere belief that frequent handwashing equals or surpasses the benefits of a flu shot. I very rarely get a cold or the flu. Of course, some people have a stronger immune system than others.

And the reason you couldn't use both measures is?

 

[Skeptic Ginger]

I guess handwashing would be of very little benefit, if we were facing an epidemic or full-blown pandemic of Swine flu. I live in a dream world.

That is again, not an evidence based conclusion. Handwashing and vaccine would both be important.

 

[Skeptic Ginger]

Apparently you are having trouble interpreting these results. So let's take a closer look. I have expanded your emphasis, you missed some key facts.

The full abstracts for Skeptigirl's evidence for the effectiveness of the seasonal flu vaccine:

http://www.ncbi.nlm.nih.gov/sites/en...RVAbstractPlus

BACKGROUND: The effectiveness of influenza vaccination against hospitalization and death can only ethically be assessed in observational studies. A concern is that individuals who are vaccinated are healthier than individuals who are not vaccinated, potentially biasing estimates of effectiveness upward. METHODS: We conducted a historical cohort study of individuals >64 years of age, for whom there were data available in the General Practice Research Database for 1989 to 1999 in England and Wales. Rates of admissions for acute respiratory diseases and rates of death due to respiratory disease were compared over 692,819 person-years in vaccine recipients and 1,534,280 person-years in vaccine nonrecipients. RESULTS: The pooled effectiveness of vaccine against hospitalizations for acute respiratory disease was 21% (95% confidence interval [CI], 17%-26%). The rate reduction attributable to vaccination was 4.15 hospitalizations/100,000 person-weeks in the influenza season. Among vaccine recipients, no important reduction in the number of admissions to the hospital was seen outside influenza seasons. The pooled effectiveness of vaccine against deaths due to respiratory disease was 12% (95% CI, 8%-16%). A greater proportionate reduction was seen among people without medical disorders, but absolute rate reduction was higher in individuals with medical disorders, compared with individuals without such disorders (6.14 deaths due to respiratory disease/100,000 person-weeks vs. 3.12 deaths due to respiratory disease/100,000 person-weeks). Clear protection against death due to all causes was not seen. CONCLUSIONS: Influenza vaccination reduces the number of hospitalizations and deaths due to respiratory disease, after correction for confounding in individuals >64 years of age who had a high risk or a low risk for influenza. For elderly people, untargeted influenza vaccination is of confirmed benefit against serious outcomes.

Vaccine recipients had equal outcomes when there was no flu around. That contradicts the single study which found no difference between vaccine recipients in or out of flu season. The contradicted study suggested the reason for less morbidity and mortality in the vaccine group was that healthier people chose to be vaccinated. This is a bit counter-intuitive since providers encourage less healthy people to get vaccinated and there is evidence people do follow their provider's advice. This study contradicts that finding and suggests the vaccine benefit shows up during flu season as you would expect.

This study also shows both healthy and less healthy people see a reduction in hospitalization and death when vaccinated.

You also seem to think the number here, 12% represents the effectiveness against the flu. Not so, it is the reduction in deaths in all respiratory infections. The reason for using this calculation is because it is not practical nor necessary to culture the organism in every pneumonia death. One assumes if deaths are lower among vaccine recipients when flu is prevalent, and the same when flu is not prevalent that the vaccine is preventing flu deaths.

You also claim this is a minor benefit. With 35,000 annual deaths from influenza, 12% more would be dying without the use of the vaccine. Annual flu vaccine would be preventing about 4,500 deaths if my rapid math estimate is correct. So again, your claim the cost of the vaccine is not worth benefit is simply warped.

http://www.ncbi.nlm.nih.gov/sites/en...ubmed_RVDocSum

BACKGROUND: Reliable estimates of the effectiveness of influenza vaccine among persons 65 years of age and older are important for informed vaccination policies and programs. Short-term studies may provide misleading pictures of long-term benefits, and residual confounding may have biased past results. This study examined the effectiveness of influenza vaccine in seniors over the long term while addressing potential bias and residual confounding in the results. METHODS: Data were pooled from 18 cohorts of community-dwelling elderly members of one U.S. health maintenance organization (HMO) for 1990-1991 through 1999-2000 and of two other HMOs for 1996-1997 through 1999-2000. Logistic regression was used to estimate the effectiveness of the vaccine for the prevention of hospitalization for pneumonia or influenza and death after adjustment for important covariates. Additional analyses explored for evidence of bias and the potential effect of residual confounding. RESULTS: There were 713,872 person-seasons of observation. Most high-risk medical conditions that were measured were more prevalent among vaccinated than among unvaccinated persons. Vaccination was associated with a 27% reduction in the risk of hospitalization for pneumonia or influenza (adjusted odds ratio, 0.73; 95% confidence interval [CI], 0.68 to 0.77) and a 48% reduction in the risk of death (adjusted odds ratio, 0.52; 95% CI, 0.50 to 0.55). Estimates were generally stable across age and risk subgroups. In the sensitivity analyses, we modeled the effect of a hypothetical unmeasured confounder that would have caused overestimation of vaccine effectiveness in the main analysis; vaccination was still associated with statistically significant--though lower--reductions in the risks of both hospitalization and death. CONCLUSIONS: During 10 seasons, influenza vaccination was associated with significant reductions in the risk of hospitalization for pneumonia or influenza and in the risk of death among community-dwelling elderly persons. Vaccine delivery to this high-priority group should be improved. Copyright 2007 Massachusetts Medical Society.

So both studies confirm exactly what I said in my previous post, which was that the flu shot varies in effectiveness from poor to good and doesn't stop many people being admitted to hospital or dying.

Where do you get this "poor effectiveness" here? Again, you don't even know what you are looking at. There are many causes of pneumonia. The influenza vaccine is not going to protect people against all pneumonia. That's ignorant. Studies report decreases in total pneumonia cases like I said, because we calculate rates based on sampling, not based on culturing each infective organism in each patient.

This study gives some idea of what is going on in the second study, which appears to show a significant reduction in risk of death:

Quote:
BACKGROUND: Numerous observational studies have reported that seniors who receive influenza vaccine are at substantially lower risk of death and hospitalization during the influenza season than unvaccinated seniors. These estimates could be influenced by differences in underlying health status between the vaccinated and unvaccinated groups. Since a protective effect of vaccination should be specific to influenza season, evaluation of non-influenza periods could indicate the possible contribution of bias to the estimates observed during influenza season. METHODS: We evaluated a cohort of 72,527 persons 65 years of age and older followed during an 8 year period and assessed the risk of death from any cause, or hospitalization for pneumonia or influenza, in relation to influenza vaccination, in periods before, during, and after influenza seasons. Secondary models adjusted for covariates defined primarily by diagnosis codes assigned to medical encounters. RESULTS: The relative risk of death for vaccinated persons compared with unvaccinated persons was 0.39 [95% confidence interval (95% CI), 0.33-0.47] before influenza season, 0.56 (0.52-0.61) during influenza season, and 0.74 (0.67-0.80) after influenza season. The relative risk of pneumonia hospitalization was 0.72 (0.59-0.89) before, 0.82 (0.75-0.89) during, and 0.95 (0.85-1.07) after influenza season. Adjustment for diagnosis code variables resulted in estimates that were further from the null, in all time periods. CONCLUSIONS: The reductions in risk before influenza season indicate preferential receipt of vaccine by relatively healthy seniors. Adjustment for diagnosis code variables did not control for this bias. In this study, the magnitude of the bias demonstrated by the associations before the influenza season was sufficient to account entirely for the associations observed during influenza season.

Right, Ivor, take one study, despite the fact the other two have different outcomes and proclaim it is the correct outcome. I posted this study for a reason. I did so because I was consciously not trying to cherry pick the data. You, however, don't seem to have the same objective view. Why am I not surprised?

 

[Deetee]

It is my sincere belief that frequent handwashing equals or surpasses the benefits of a flu shot. I very rarely get a cold or the flu. Of course, some people have a stronger immune system than others.

What is the basis for this belief? Do you realise that flu is primarily spread by droplets which are inhaled? If someone coughs in your face, do you rush to the bathroom to wash your hands?

I am not saying influenza virus cannot be transmitted via contaminated hands/fomites in a situation where the environment has become contaminated (as can also happen with rhinovirus - the common cold), but hand washing is highly unlikely to prevent direct infection from a contact.

 

[Dymanic]

Do you realise that flu is primarily spread by droplets which are inhaled?

It's always hard to tell how good a match the current year's vaccine is until well into the season, and while some of us find that an interesting and important question, most people would probably find it preferable to opt out of that investigative process by simply avoiding exposure.

That might be easier to accomplish if more were known about the mechanical details of influenza spread. Unfortunately, the relative importance of airborne/droplet versus contact/fomite transmission is still an open question at this point (as are questions regarding the relative importance of airborne versus droplet and contact versus fomite).

The best bet is to get the vax, avoid crowded elevators and such during the peak of the season, and wash your hands a lot.