Almost 20,000 cases of flu have been reported in New York State so far this season - more than four times the number of cases last winter.
The flu outbreak has reached epidemic proportions across the US. Last week 7.3% of US deaths were caused by pneumonia and the flu.
The governor of New York State, Andrew Cuomo, has declared a public health emergency because of the severity of this year's influenza season.
Experts recommend flu vaccines, which have been found to be 62% effective.
The 2012-13 flu season is said to have started earlier than usual, with many cases of the H3N2 strain, which can be severe.
The only states without widespread flu were California, Hawaii and Mississippi.
Flu symptoms can include fever, cough, runny nose, body ache and fatigue.