COVID-19 activity increased across all indicators in the past fortnight, with case numbers, hospital figures and sewerage monitoring results rising, data from NSW Health shows.

There has been a 20.6 per cent increase in notification for the virus.

In order to protect patients and staff, surgical masks have been temporarily reintroduced in clinical areas in Illawarra Shoalhaven Local Health District hospital and health facilities.

"The risk of transmission remains high," a health district spokeswoman said.

"This is a short-term mitigation measure to reduce the risk of COVID transmission and to help keep patients, staff, volunteers, and visitors safe."

Anyone experiencing cold or flu symptoms should stay at home to protect others.

"They should postpone visiting friends and family in hospital and avoid visiting other high-risk settings such as aged or disability care facilities or people who are at higher risk of severe illness," the spokeswoman said.

Staff treating patients with, or suspected to have COVID, will continue to wear personal protective equipment.

Meanwhile, the number of Australians getting vaccinated against COVID, shingles and other serious diseases has dropped, prompting a plea to reset national immunisation strategies to target more high-risk groups.