More seniors were hospitalized with influenza during this year’s flu season than at any time over the past 10 years, the Centers for Disease Control and Prevention reports.

About one in every 300 older Americans — 0.3 percent — were admitted to the hospital with flu, according to CDC records.

A likely reason: The flu vaccine was a bad match for the most common strain of the virus circulating this year — Influenza A (H3N2) — because the virus mutated between the time the vaccine was developed last spring and the start of the flu season last fall.

As a result, the vaccine offered very little protection against this particular strain of influenza, which typically kills about 30,000 Americans each year — many of them seniors and young children.

According to the latest CDC update:

• Flu activity continues to decline and flu-like illness is below national baseline levels for most of the nation.
• Three states (Connecticut, Massachusetts, and New York) continue to report widespread flu activity.
• Influenza B viruses now account for 89 percent of all influenza viruses reported.
• A total of 17,584 laboratory-confirmed influenza-associated hospitalizations have been reported since October 1. This translates to a rate of 64.3 hospitalizations per 100,000 people — far higher last year’s, rate which was 43.9 per 100,000 people.
• The hospitalization rate in people 65 years and older is about 316 per 100,000, which is the highest hospitalization rate recorded since data collection on laboratory-confirmed influenza-associated hospitalization in adults began during the 2005-2006 season.
• The death rate from this year’s flu season is 6.7 percent — slightly below the 6.9 percent threshold CDC considers epidemic levels.
• Influenza A (H3N2) viruses were the dominant strain during the 2014-2015 flu season, accounting for more than 99 percent of all subtyped influenza A viruses.