Officials say that flu cases are now widespread across the state, and health workers are being ordered to take precautions.
Health workers are being told to either get a flu shot or wear surgical masks when patients are present.
The mandate from New York State Health Commissioner Dr. Nirav Shah follows confirmed flu cases in more than 45 New York State counties and in all five boroughs.
The rule applies to more than 4,000 hospitals, clinics, diagnostic centers, nursing homes, hospices and home care agencies.
Doctors, nurses, students, volunteers, contractors and even some cafeteria workers all must abide by the order.