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Why You Still Should Have Gotten That 'Lousy' Flu Shot

Okay, we know this year's flu shot wasn't exactly the most effective vaccine ever formulated.

It seemed a lot of people who were immunized got sick anyway, and the reason was wickedly simple: the main strain going around had mutated, and brushed off the protection of the vaccine like a speck of dust.

That strain was H3N2, one of four strains supposedly covered by the immunization.

Yet now we are still dealing with influenza -- in March, no less -- and it's mainly nailing people who were not immunized.

The reason for this is simple: the strain making the rounds is not H3N2, it's one of the other four in the vaccine, an influenza B virus. (H3N2 is an influenza A strain).

So even though we knew the vaccine was a weakling, we kept on telling you to get a flu shot, and this is why. We had a feeling one of the other strains would rear its ugly head at some point later in the season. Influenza B became the predominant strain in mid-February.

The good news is that this B strain isn't running rampant like H3N2, but it's still knocking people down, and putting people in the hospital.

Therefore, it's still not too late to get a flu shot, especially if you are in a high risk group.

Now here's a little summary of the year. It was an ugly one:

- The effectiveness of the vaccine against H3N2 was only 18 percent. Lousy.

- Reasearchers are now looking at what flu bugs are circulating around the world and expected to hit the U.S. next fall. Next year's flu immunization will be completely different than this year's, with lots of tweaking against H3N2, and the addition of protection against two other strains. In essence, a major overhaul.

- In Colorado, the worst week of the flu year struck right after Christmas. There were 580 hospitalizations that week.

- For the season to date, the total number of hospitalizations is 3,044, which is the highest number since we started keeping track in the year 2004. This figure does not include people who went to the doctor with flu, or just stayed home to ride it out.

- People over age 65 were the hardest hit this year, so were babies and toddlers. But flu even nailed people in the robust 25-49 age group. No one escaped the wrath of the season.

Right now, flu activity is no longer deemed "widespread" in our state; it's mainly localized outbreaks. But it's still out there.

Whatever you want to call it, it has been a heckuva year. One we would rather not see ever. And if you were one of the "unluckies" to get the flu, I'm sure you feel the same way.

Dr. Dave Hnida is CBS4's Medical Editor. He blogs about the latest studies and trends in the health world. Read his latest blog entries, check out his bio or follow him on Twitter @drdavehnida

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