Hospitals across the US are bringing in stringent rules restricting the number of visitors that can see patients in an effort to prevent the spread of H1N1 influenza.

Salem Hospital and West Valley Hospital in the US state of Oregon require that visitors to all hospitalised patients must be 12 years of age or older and without any flu symptoms.

Salem Hospital also restricts those below 18 years of age from visiting expecting mothers and newborns because they are at a higher risk of contracting the flu.

Lahey Clinic and Beverly Hospital in the US state of Massachusetts have also implemented similar guidelines for visitors.

The precautionary measures are temporary and based on recommendations from the Centers for Disease Control and Prevention and the Department of Public Health.