Victorian health authorities have issued a measles alert after a woman attended the Australian Grand Prix while possibly infectious.

A measles health alert has been issued in Victoria after a woman went to the Grand Prix in Melbourne while she may have been infectious.

The woman, who is in her 40s, remains isolated and is being treated in hospital after acquiring the illness in the Northern Territory, where there is an outbreak.

Health authorities say the woman may have been infectious while attending the Australian Grand Prix at Albert Park last weekend.

While at the Grand Prix, the woman was at Jones Stand, the Gate 2 entrance and food areas at Gate 1 on Saturday.

On Sunday, she was at the Fangio Stand, the Gate 2 entrance, and food areas at Gate 1.

She also visited Woolworths in Braybrook on Sunday and Monday.

Victoria's chief health officer Brett Sutton said the case is a timely reminder for people to ensure they are vaccinated.

"Anyone who is unvaccinated is at highest risk of contracting measles," he said.

People born in or after 1966 may be susceptible to measles, especially if they are planning to travel overseas.

Free measles-mumps-rubella (MMR) vaccines are available from GPs and some pharmacies.

Measles is highly infectious and symptoms include fever, a severe cough, conjunctivitis and coryza, followed by a rash starting on the face.

Measles patients can be infectious roughly five days before and four days after the rash appears.