in Check It Out, Futurist, Meddling

Flu shot effectiveness below 50 percent

My friends are making noise about getting a flu vaccine. I am not anti-vaccine at all, but not all vaccines are the same. And not all flu vaccines are the same, either. Each season’s flu vaccine is a coin toss whether it will actually work. According to CDC statistics, patients 65 or older who got a flu shot during the 2012-2013 season were only protected from flu an abysmally-low 9% of the time.

There is also evidence from the CDC that repeatedly getting flu shots makes you more susceptible to getting the flu.

There are a lot of claims being made about the flu vaccine, including a lot of hype. I think it’s important to pay attention to what the science tells you.

The flu vaccine was 47% effective against medically attended flu for all influenza strains in the 2011-12 season, and being vaccinated the year before lowered effectiveness, according to a study yesterday in Clinical Infectious Diseases.

US researchers from the Centers for Disease Control and Prevention and elsewhere looked at complete data for the season, which was relatively mild and peaked late. They found an overall vaccine effectiveness VE of 47% for preventing medically attended flu.

VE against 2009 H1N1 was 65%, but against H3N2, which was the predominant strain during the 2011-12 season. VE was only 39%. Its effectiveness against type B strains was 58% but was actually lower against the Victoria strain included in the vaccine 52% compared with the Yamagata strain not included in the vaccine 66%.

The investigators also noted a statistically significant difference between VE for those who received a flu vaccine the year before 33% and those who did not 56%.

via Flu Scan for Nov 14, 2013 | CIDRAP.