Parents of small children and people in high-risk groups are being urged to set a reminder for May 1 to phone their GP or find a local chemist and book a flu jab ahead of winter.

NSW Health's Communicable Diseases Director, Dr Vicky Sheppeard said most GP clinics should receive their Commonwealth flu vaccines by next month.

"Now is a great time to set a reminder in your phone or circle the date in your calendar, particularly if you or your family are in a high-risk group, to ensure you get your flu jab," Dr Sheppeard said.

"There have already been 7,584 recorded flu cases in NSW during the warmer months so the best protection ahead of winter is to be vaccinated to build up resistance."

More than 250,000 flu vaccines have been delivered so far, including over 42,000 to aged care facilities across the state.

"Flu vaccines have already been distributed to aged care facilities but for the wider population, supplies should be with their GP by May 1," Dr Sheppeard said.

So far this year, two strains of influenza A virus are causing most of the infections in NSW, similar to the strains that circulated in 2018.

Dr Sheppeard said free vaccines will again be available through GPs for all children aged from six months to under five years of age, under the NSW Government's $2.6 million program.

Based on orders for vaccine in 2019, NSW Health is hopeful more children aged between six months to five years will be vaccinated against flu in 2019.

The NSW Government has invested around $130 million in the 2018-19 Immunisation Program budget, including Commonwealth and state vaccines.

"Free flu vaccines are also available for pregnant women, Aboriginal people, those aged over 65, and anyone with conditions such as asthma, diabetes, and heart disease," Dr Sheppeard said.

People who are not eligible for free vaccines can get vaccines on the private market from their GP or an eligible pharmacist.

Influenza vaccines are recommended for children and adults to reduce their risk of flu and spreading it to vulnerable people.

"Last year we had the mildest flu season in five years but as we all remember, more than 650 people died from influenza-related illness in 2017," Dr Sheppeard said.

"Thanks to many factors, including the vigilance of the community last year, we avoided repeating the deadly flu season of 2017. We must not be complacent this year."

In addition to booking a flu jab, people are reminded that to help reduce the spread of flu, sneeze into your elbow, wash your hands regularly and stay home if you are sick.