This brings the total number of cases in NSW to 40 since Christmas last year.

Both of the new cases were in young men who were unsure if they had been vaccinated against measles in the past.

They visited a number of locations in Dubbo, Walgett, Parkes and Wagga while infectious, including:

NSW Health Director of Communicable Diseases Vicky Sheppeard said none of the locations visited by the men pose an ongoing risk.

However, people who may be susceptible to measles and were at the same locations at the same time as the men should be alert for signs and symptoms of measles until May 18 2019, as it can take up to 18 days for symptoms to appear following exposure to a person with measles.

"Symptoms to watch out for include fever, sore eyes and a cough followed three or four days later by a red, spotty rash that spreads from the head to the rest of the body," Dr Sheppeard said.

"Measles is highly contagious and is spread in the air through coughing or sneezing by someone who is unwell with the disease.

"Anyone who develops symptoms of measles should phone their GP to ensure they don't wait alongside other patients before seeing their doctor."

"People born before 1966 are likely to have had measles as a child and are considered immune. For people born during or after 1966, the best protection against measles is receiving two doses of measles vaccine."

Dr Sheppeard said the measles-mumps-rubella vaccine is safe and provides effective protection against measles.

"It's free for anyone born during or after 1966 who hasn't already had two doses," she said.

"If you're unsure whether you've had two doses, it's safe to have another.

"While the risk of infection is low in fully-vaccinated people, health experts urge anyone who comes into contact with someone who has measles to remain alert for symptoms."

For more information on measles visit:

https://www.health.nsw.gov.au/Infectious/measles/Pages/key-facts.aspx