(Reuters) - New York Governor Andrew Cuomo declared a public health emergency on Saturday, giving pharmacists permission to administer flu vaccinations to more people as officials seek to stem the worst flu outbreak in that state in several years.

Cuomo's order came a day after federal health officials said that fast-spreading influenza had officially reached epidemic proportions in the United States, following an early start.

Nine of the 10 U.S. regions had "elevated" flu activity last week, and 20 children across the country have died, the Centers for Disease Control and Prevention said on Friday.

In New York, the governor's office said 19,128 cases of influenza have been reported this season, compared with 4,404 positive laboratory tests reported for the entire 2011-2012 season.

"We are experiencing the worst flu season since at least 2009, and influenza activity in New York state is widespread, with cases reported in all 57 counties and all five boroughs of New York City,"