The spray was only to be used for children between two and 17.
But the province's chief medical health officer says only 38,000 doses of a total 150,000 available had been administered as of early November.
Dr. James Talbot says the lower-than-expected demand means the nasal spray is now available to everyone.
The nasal spray has a shorter expiry date than traditional needle vaccinations, so it can't be stockpiled as easily.
Flu shots and spray are available at immunization clinics, in doctor offices and at some pharmacies.