Cdc mandating h1n1 shot
Here's how they often measure vaccine effectiveness, especially I've noticed for flu vaccines.
"Vaccine effectiveness was estimated as 100% x (1 - odds ratio [ratio of odds of being vaccinated among outpatients with influenza-positive test results to the odds of being vaccinated among outpatients with influenza-negative test results])"In other words, if the flu vaccine makes recipients four times a likely to get another respiratory disease, and does nothing whatsoever to help with flu, it is calculated to have an effectiveness of 75%If it makes you twice as likely to get flu, and four times as likely to get another respiratory disease, then it is counted as having an effectiveness of 50%. id=386In response to this comment “The year I got a flu shot is the only year I got sick”, I would like to give out a rationale that explain the situation.
The official government figure for the annual number of deaths caused by influenza infection remains at 36,000.
Why this figure has not changed during the course of a decade is anyone’s guess.
"There was “unexpectedly low vaccine effectiveness for the influenza A strain among older children compared to other age groups,” especially for those who had gotten previous annual flu shots."There is a good explanation for that.