Flu shot, adverse effects?

[EdEarl]

As I understand some statistics on flu shots only include people who have the flu and have or have-not had a flu shot, for example rates of coronary events while sick with flu. Some studies track side effects or suspected side effects of flu vaccination, for example Guillain-Barré syndrome. Has anyone checked for the rate of coronary event (or other complications from flu that may be mediated by having a flu-shot of people who have a coronary event (or other complication) who do not have the flu but have or have-not had a flu shot?

 

People who have not had flu or flu shots may or may not have a lower heart attack rate than those who have had flu or flu shots; however, one would have to account for older people tending to have more heart attacks and more flu or flu shots, and other as yet unidentified mediating factors--meaning other unidentified things that change both heart attack rates (as age does) and number of times one has had the flu or flu shots (as ages does).

 

It seems to me that unidentified mediating factors confound results from such a study, and consequently mean such studies might not be attractive to researchers. I would argue that if data is already available from insurance files, that insurance companies should have done them. If they have been done, have they been published?

 

 

[John Cuthber]

Would it matter?

What has been checked very carefully is the overall death rate with and without flu shots.

 

Even if it marginally raises the risk of some conditions- for example, coronary disease, the overall effect is beneficial so the benefits must outweigh that increase.

 

Having said that, I suspect that the data is there somewhere as part of the studies into vaccinations..

Indeed, a bit of googling gave me this

http://www.medicalnewstoday.com/articles/267777.php

which says

"As the flu season is fast approaching, a timely study links receiving a flu vaccination with a lower risk of serious cardiovascular events, including heart failure or heart attack. And researchers say patients who have experienced recent acute coronary syndrome see the greatest effect."

[CharonY]

 

 

It seems to me that unidentified mediating factors confound results from such a study, and consequently mean such studies might not be attractive to researchers.

 

Pretty much the whole field of epidemiological research has these issues. Considering that it still exists probably means that these are not unattractive to researchers.