Deputy Chief Health Officer Dr Brett Sutton confirmed cases of summer flu are significantly higher than the same time last year, with more than 2800.

In the Grampians region alone, there have been 71 cases reported so far this year, compared to 27 at the same time in 2018.

"It's certainly more than double statewide, this year, and there'll be a lot more out there that haven't been diagnosed," Dr Sutton told 3AW radio.

"It's definitely one of the biggest summer seasons we've seen.

"It is unusual for children to die, it's a relatively rare thing. But it's a reminder to all of us we're not just protecting ourselves when we get the vaccine, we're helping to protect those who are at risk, including children."

The Metropolitan Remand Centre has also had a flu outbreak, with those affected advised to be in isolation until the infection passes.

Dr Sutton said the higher number of cases could be related to international travel, greater reporting and more doctors conducting tests.

While anyone is vulnerable, the elderly, pregnant women and children are most at risk.

"We've always emphasised the dangers of flu - that's why we've always pushed the vaccination and other measures people can take to stay away from others when they're unwell, to make sure they don't go to work, to make sure they wash their hands, to cough into their elbow," he said.

While people can be infected any time of year, the season officially begins in April and people are advised to get the flu vaccine from mid-April onwards.

- AAP

Have you signed up to The Courier's variety of news emails? You can register below and make sure you are up to date with everything that's happening in Ballarat.