People who visited Wollongong Hospital on Monday are being advised to watch for symptoms of chickenpox, after a clinician was diagnosed with the infection.
A similar alert has been put out for people who visited Shoalhaven District Memorial Hospital between August 19 and 23.
A Wollongong Hospital spokesperson said there had been no further cases reported, but the incubation period for chickenpox meant symptoms were unlikely to be showing just yet.
Symptoms usually occur two weeks after exposure.
Chickenpox begins with a slight fever, runny nose, feeling generally unwell and a skin rash.
The rash begins as small lumps that turn into blisters and then scabs and appears over three to four days.
Most people recover from chickenpox but sometimes the infection can lead to serious complications, such as pneumonia and inflammation of the brain.
Anyone who has not had chickenpox or who has not been vaccinated in the past can get chickenpox.
Illawarra Shoalhaven Local Health District Infection Management and Control Service manager Joanna Harris said patients and staff potentially exposed to the virus were being notified.
"We are now in the process of contacting all of the patients who may have had contact with the clinician on the days in question," she said.
"People who visited the hospital on those days are also being encouraged to be mindful of symptoms."
People with symptoms are advised to see their GP, but to call ahead and advise you may have chickenpox. Likewise if people need to visit an emergency department.
Anyone diagnosed with chickenpox should stay away from other people for five to seven days after the rash first appears.