Mask-wearing is now compulsory at all HSE sites in Kerry and Cork including University Hospital Kerry, community hospitals and primary care centres.
Visiting times to hospitals in both counties have been restricted to two visitors only between 6pm and 8pm.
The HSE South West has made these decisions because of the upsurge in influenza, COVID-19, and RSV cases.
The HSE says patients admitted to an acute hospital in the Kerry/Cork area may have to be transferred to another acute hospital in the region for treatment due to the very high number of patients with respiratory viral illnesses.
These measures will be lifted as soon as possible when clinical circumstances allow.