With more than 360 confirmed flu cases in the Illawarra Shoalhaven Local Health District already this year, Curtis Gregory reminded people to get their flu shot.

"While we might all take flu for granted as a common winter disease, it can be deadly," he said.

"In 2017, we had a significant flu season where more than 650 people died across the state. We cannot afford to be complacent."

Mr Gregory said pregnant women, young children and the elderly would be a major focus of NSW Health's 2019 flu campaign, which launched this week.

Free vaccines were available for these groups, as well as Aboriginal people and anyone with chronic conditions like asthma, diabetes and heart disease.

"We've had a lot of summer flu - for instance there's been 363 notifications throughout the district this year compared to 101 for the same period last year," he said.

"While that doesn't necessarily translate into a large flu season, we're encouraging people to get vaccinated and have good hygiene practices, so we don't get a repeat of the 2017 flu season.

"There was a good uptake of the vaccine in 2018, and in this region we saw the lowest number of flu cases in five years."

Mr Gregory said from now until the end of June was the optimum time to get the flu shot, to ensure it provided protection during the peak flu months of July and August.

One million vaccines have been delivered across the state, and they protect against four flu strains (two A and two B strains).

"The flu vaccine is good, but it doesn't offer 100 per cent protection," Mr Gregory said.

"But if you're vaccinated and do get the flu, you're likely to have it for a lesser period of time, and have less severe symptoms."

To prevent the spread of flu, people are urged to sneeze or cough into their elbow, wash their hands regularly and stay home if they're sick.

Mr Gregory also urged people with symptoms including fever, cough or runny nose, to postpone visits to aged care facilities or childcare centres.