Inmates in Hawaii prisons who are in high-risk groups will be receiving swine flu vaccines.

Dr. Marc Rosen, medical director of the state Department of Public Safety, said prevention is needed to reduce the spread of the illness to other inmates in the close quarters of correctional facilities.

Swine flu vaccination will be voluntary. But Rosen said inmates will be encouraged to get vaccinated.

High-risk groups include pregnant inmates and those with chronic health problems.

Medical staff members in contact with inmate-patients also will receive vaccines to reduce the risk of passing the virus to family members and the community at large.

Some 4,000 inmates are in prison facilities in Hawaii.