Health authorities are pleading with members of the public to get their flu shot as dozens of influenza outbreaks ravage NSW residential care homes and continue to claim elderly lives.

NSW Health data released on Friday reveals 66 confirmed influenza deaths in the six months to June 30.

Of them, 26 were in residential care facilities and among people with other significant health issues.

The state's residential care facilities have reported 112 outbreaks this year - 26 in the latest reporting week alone.

A mental health facility and a hospital were also hit with outbreaks in the past week.

NSW Health said unwell visitors may be putting loved-ones at risk.

"While we acknowledge the importance of visiting family members and friends in aged-care facilities, if you are unwell with the flu we are asking people to stay home and minimise contact with other people if possible, until you have recovered," communicable diseases director Vicky Sheppeard said in a statement.

Dr Sheppeard also called on NSW residents to get the flu vaccine.

"It is not too late to get vaccinated, we want to remind people that the flu vaccine is still the best protection, so please take advantage of the free jab," she said.

The warning comes after a nursing home at Unanderra, near Wollongong, was placed in lockdown following an outbreak which began on the June long weekend.

Approximately 20 residents and 20 staff have presented with flu symptoms, manager Robert O'Shea told AAP on Wednesday.

Five residents were hospitalised and three died.

The facility is no longer in "outbreak control", a NSW Health spokeswoman told AAP on Friday.