CDC officials think this year's flu shot will work better than last year's

It's called A/Switzerland/9715293/2013, and it's one of the reasons why your flu shot might not have worked last year.

The viral strain of H3N2 flu was behind most of the illnesses during last year's flu season, the Los Angeles Times reports, but it surfaced too late to be included in vaccines for the United States. The overall effectiveness of flu vaccines was just 23 percent, the Centers for Disease Control and Prevention says, meaning those who got vaccinated were 23 percent less likely than those who did not receive flu shots to get sick enough to go to the doctor.

This year, federal officials said flu shots and flu mists offer protection against the strain, as well as H1N1 viruses similar to the strain that caused swine flu in 2009 and 2010. Officials said they recently found three patients who came down with the flu from viral strains never before seen in people — one in Minnesota in July, one in Iowa in August, and one in Michigan in August. The strains were similar to those found before in pigs, and all three said that they had been in direct contact with pigs in the week before they became ill. Each one has made a full recovery, and the CDC says there's no evidence that these new viruses were spread to other people.

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The CDC recommends almost everyone over the age of six months get the vaccine, but is reminding people that even if you do get a shot, "it is not possible" to predict which flu strains will spread or how the vaccine will fight them.