Effectiveness of vaccine against pandemic influenza/ BMJ

If you read the second post below this one, you will see evidence from several countries that suggests a previous seasonal flu vaccine may actually increase the risk of getting flu, and may worsen one’s short and long-term immune response to a newer flu vaccine.

As if that wasn’t enough reason to avoid getting routine flu vaccinations, it seems flu vaccine may actually increase your risk of getting flu in the first two weeks after flu vaccination!  That was a Danish finding in a study including 80,000 swine flu-vaccinated people under age 65 who were thought to be at increased risk from a flu infection.  The study is of high quality, published in the BMJ Jan 25.

An increased risk of laboratory confirmed H1N1 infection was observed during the first 1-7 days after receiving the pandemic vaccine, with vaccine effectiveness estimates of −112% (95% confidence interval −187% to −56%) [Negative effectiveness means you have an enhanced chance of getting flu] compared with those who did not receive either the pandemic or the seasonal influenza vaccines. In the following 8-14 days, no significant effectiveness from the pandemic vaccine was observed, and effectiveness was 49% (10% to 71%) more than 14 days after receiving the vaccine (table 2⇓). Those who received only the 2009-10 seasonal influenza vaccine had an increased risk of laboratory confirmed H1N1 infection compared with those who were not vaccinated (hazard ratio 2.31, 95% confidence interval 1.65 to 3.23; table 2)…

Did the vaccine keep people out of the hospital?  In other words, did they have a milder illness as a result of vaccination?

An increased risk of H1N1 related admission to hospital was observed during the first 1-7 days after receiving the pandemic vaccine, with vaccine effectiveness estimates of −258% (95% confidence interval −464% to −127%) compared with those who did not receive either the pandemic or the seasonal vaccines… 

Those who received only the 2009-10 seasonal influenza vaccine had an increased risk of H1N1 related hospital admission (hazard ratio 2.55, 95% confidence interval 1.38 to 4.70; table 2)…

If you got only the seasonal flu vaccine, you were 2.5 times more likely to be admitted to hospital with swine flu than if you received no flu vaccine at all!  And if you happened to get the swine flu vaccine, you were 2.6 times as likely to wind up in the hospital in the week after vaccination as people who got no flu vaccine at all!

How could this be, you might ask.  It isn’t hard to theorize why:

“… one group of researchers suggested that repeated immunisations effectively block the robust, complex, and cross protective immunity afforded by previous infection. This might be a possible explanation for the Canadian findings and also a possible explanation for the finding in the present study…”

Given these facts, I have a hard time with public ‘health’ officials who want to force Americans to get yearly flu vaccines. 

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