Flu Vaccine Study

[Fire_Medic_Dave]

AUTHORS' CONCLUSIONS: Influenza vaccines are effective in reducing cases of influenza, especially when the content predicts accurately circulating types and circulation is high. However, they are less effective in reducing cases of influenza-like illness and have a modest impact on working days lost. There is insufficient evidence to assess their impact on complications. Whole-virion monovalent vaccines may perform best in a pandemic.

http://www.ncbi.nlm.nih.gov/pubmed/17443504?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=2&log$=relatedreviews&logdbfrom=pubmed


This may seem like a dumb question, so bear with me. Are they saying that people experiencing flu like symptoms don't actually have the flu or just that they didn't confirm whether or not they had the flu?

David

[Chulanowa]

1. It's the predicting part that's hard...

I work in a nursing home, so flu shots and other such tests / vaccinations are darn near mandatory. We all got flu shots for what was predicted to be the most likely strain to hit us...

And it was the wrong strain. Someone visited while either sick or pre-symptom... And, well... Bad Things happened. A full wing of the facility fell ill, with some residents being unable to fully recover. Most of the employees caught it, too, which only made the situation worse - taking care of sick people while at half staff isn't good for ANYONE.

[LaurenG]

2. More likely they weren't tested to see if it was the flu.

I work in the medical field and 16 people in my office received the vaccine. 6 of us tested positive for flu last week. It was a bummer that's for sure. According to the vaccine rep I spoke with yesterday the makers of the vaccine want to see at least a 70% effectiveness rate.

[xchrom]

3. why couldn't it be a combination of both?

i'm there are illnesses that look like flu -- respiratory infections, complications, etc and i'm sure
that there are people who get the flu but don't visit the doctor to see -- even though they've had the vaccine.

[Fire_Medic_Dave]

6. Well it wouldn't make sense to blame the flu if that wasn't the cause of the illness.

[xchrom]

15. i'm just sayin -- what's a 'flu-like' illness?

could be one -- could be the other.

[Fire_Medic_Dave]

16. That's what I'm saying.

[theoldman]

4. Most people just have a bad cold or bronchitis, not the flu.

Flu virus will knock you on your ass for weeks. It will kill you if your are very young or very old.

[Fire_Medic_Dave]

8. Yes but they claim some effectiveness of the flu vaccine.

A claim that the flu vaccine can somehow provide immunity to other pathogens would be an incredible one to say the least.

David

[mike_c]

5. parsing....

Influenza vaccines are effective in reducing cases of influenza, especially when the content predicts accurately circulating types and circulation is high.

Vaccines all work best when they accurately immunize against the actual virus in circulation. Flu vaccines are no different. If the vaccine content-- the specific flu antigens presented in the vaccine-- match the flu virus actually circulating in the wild, the vaccines provide effective protection to the immunized.

However, they are less effective in reducing cases of influenza-like illness and have a modest impact on working days lost.

Most cases of influenza-like illness are likely not really flu virus or are flu strains not immunized against. Even if the vaccine is effective against target flu virus, it won't work if patients catch something else. Since the majority of cases are probably something else, vaccines have relatively little impact on work days lost (to other illnesses).

There is insufficient evidence to assess their impact on complications.

If vaccines reduce the incidence of flu-- real flu, the virus in the vaccine mix at any given time-- one would expect them to reduce the incidence and perhaps the severity of post-infection complications. However, there is insufficient data to actually support that assumption.

Whole-virion monovalent vaccines may perform best in a pandemic.

In the event of a pandemic flu strain, standard mixed influenza or best guess influenza vaccines would not be as effective as vaccines made from the actual pandemic strain, and whole-viron vaccines present the greatest number of potential epitopes to the immune system. HOWEVER-- and this is a big qualification-- it takes time to develop and produce clinical quantities of vaccine, and whole viron pandemic specific vaccines cannot begin development and production until after the pandemic begins. Otherwise, there's no good way to anticipate which strains to make vaccine from. This limitation is being worked on, but it's still a big problem IIRC.

[Fire_Medic_Dave]

7. It is this phrase I'm having a problem with.

However, they are less effective in reducing cases of influenza-like illness and have a modest impact on working days lost.


Maybe it's just me but I wouldn't expect the Flu vaccine to have any affect an influenza like illness that was caused by another pathogen. Are they saying that flu vaccines are somewhat effective at protecting against other pathogens? If so that is one incredible claim.


David

[mike_c]

9. no, I don't think so....

I think they're saying that MANY cases that present with influenza symptoms and are diagnosed as influenza are actually other illnesses. Statistically, these show up in public health records as putative vaccine failures, even though-- as you pointed out-- there is absolutely no reason to think flu vaccine should immunize against them.

Even if you could achieve 100 percent vaccination rates with a 100 percent effective vaccine-- not possible, but I'm just sayin'-- you'd still expect a statistically significant number of "flu" patients who actually have something else.

[Fire_Medic_Dave]

12. Don't they usually test for the flu now.

[uppityperson]

13. That depends. We have flu test kit at nursing home, but

they haven't used it on anyone there in the last few weeks (just returned to work there) even though there are people who have had flu-like symptoms (fever, then cough cough cough cough cough). I've had the flu but never been tested, just stayed home until was non-contagious as I am one of "those sort" of people.

I think it depends on whether or not you go in to get tested and most people I know don't.

[Jim__]

10. I'm not sure if this clarifies anything, but, FWIW

At little before the part of the report that you cited there is a MAIN RESULT section:

MAIN RESULTS: Forty-eight reports were included: 38 (57 sub-studies) were clinical trials providing data about effectiveness, efficacy and harms of influenza vaccines and involved 66,248 people; 8 were comparative non-randomised studies and tested the association of the vaccines with serious harms; 2 were reports of harms which could not be introduced in the data analysis.Inactivated parenteral vaccines were 30% effective (95% CI 17% to 41%) against influenza-like illness, and 80% (95% CI 56% to 91%) efficacious against influenza when the vaccine matched the circulating strain and circulation was high, but decreased to 50% (95% CI 27% to 65%) when it did not. Excluding the studies of the 1968 to 1969 pandemic, effectiveness was 15% (95% CI 9% to 22%) and efficacy was 73% (95% CI 53% to 84%). Vaccination had a modest effect on time off work, but there was insufficient evidence to draw conclusions on hospital admissions or complication rates. Inactivated vaccines caused local tenderness and soreness and erythema. Spray vaccines had more modest performance. Monovalent whole-virion vaccines matching circulating viruses had high efficacy (VE 93%, 95% CI 69% to 98%) and effectiveness (VE 66%, 95% CI 51% to 77%) against the 1968 to 1969 pandemic.

Correct me if I'm wrong, but flu vaccine is effective at preventing you from getting the flu. So, my intepretation of that is that people who get a flu vaccine are (17 to 41%) less likely to get an influenza-like illness. Do people come down with influenza-like illness when their body succesfully fights off the flu - but fighting off the flu may have after-effects that are flu-like?

It is probably clearer if you have access to the whole report. I don't have any medical background, so I can only guess.

[Fire_Medic_Dave]

11. Some of the studies could have been statistical...

that only compared the numbers of patients who reported flu like symptoms but were not comfirmed flu cases. As has been pointed out, some portion of those are illnesses caused from another pathogen. That is where the "decreased" effectiveness probably comes from.

David

[uppityperson]

14. I see it as possibly flu, possibly not, since we didn't test we don't know.