The state Health Department says influenza is now prevalent in New York state, which means health care workers who haven't had a flu shot must wear procedural masks around patients.
The agency says there have been over 1,800 confirmed cases of influenza in 54 counties and all boroughs of New York City. More than 600 required hospitalization.
Influenza season typically runs from October through May, often peaking in February.
Health Commissioner Dr. Howard Zucker says everyone over 6 months old is encouraged to get a flu shot as soon as possible. He says the vaccine is especially important for people at high risk of complications from flu, including children under 2, pregnant women and adults over 65.