In the 1880s, the word "coop" was slang for jail. So when someone "flew the coop," they broke out of jail. There were no chickens in the picture anywhere.

The latest reports on this year's flu vaccine make it sound like the inoculation was more chicken than anything — running away from the H3N2 flu virus instead of preventing infection from it.

Some studies show that 97% of this year's flu is from H3N2, and the Centers for Disease Control and Prevention (CDC) says the current vaccine is only 16% effective in protecting you from mild or moderate infection with that strain, even though its part in the vaccine was updated from last year. (The strain mutated in an unexpected way.)

But that doesn't mean this year's flu vaccine can't save you from serious flu symptoms and even death.

Furthermore, getting your flu shot year after year provides cumulative protection from distinct H3N2 viruses. So even if this year's vaccine misses that mark, chances are your body's defense system won't.

A study in Clinical & Translational Immunology found that cumulative and staggered influenza vaccination generates high antibody responses and "influenza vaccination should be considered for its benefits for immediate protection and future virus encounters."

When someone says "I told you I didn't need a flu shot," remind them that this is a battle fought over decades, not months or years, and anyone who gets an annual flu shot is in much better position to beat the flu in any given year than people with sporadic or no vaccinations.