The infected patients have been admitted into hospitals in Teruel and Zaragoza as a result of the outbreak.
Local health authorities said on Thursday the H1N1 strain of influenza A virus involved was unusual but covered by standard medical guidelines.
Among the measures being taken are vaccination of family members and isolation of patients, local daily El Periódico de Aragon reported.
Health authorities are now warning people of the importance of prevention. Vaccinations are available at health centres until March.
"You don't have to belong to a risk group" such as children or people aged over 65 years of age, the regional health department said of the outbreak.
Bird flu rose to international prominence in 2009 after a global pandemic.
Most cases of swine flu — a respiratory disease which originates in birds — are relatively mild, but severe cases can lead to hospitalization or even death.