Health officials warn this year's flu virus is the same that once killed over 50 million people.

Flu season has officially begun and the CDC announced the dominant strain this year is H1N1.

It's the same flu virus that killed over 50 million people over 100 years ago. The 1918 influenza pandemic devastated communities and took the lives of over 675,000 Americans, according to the CDC.

H1N1 viruses have been the most commonly identified flu virus this flu season, the CDC reports. However, recently, H3N2 viruses have popped up in the southeastern region of the United States.

According to this week’s CDC FluView report, the flu virus has been reported more than normal nationally and continues to increase.

Nine states, including New York, are experiencing high influenza activity, officials say.

In New York, during the week of Christmas, there were 2,117 laboratory-confirmed influenza reports, a 72% increase over last week, according to the New York State Department of Health. 58 New York counties reported new flu cases, including every county in the Hudson Valley.

An annual flu vaccine is the best way to protect against influenza and its potentially serious complications, the CDC reports.

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