Julie Theobald dies suddenly from common illness - leaving behind 13 children

An Aussie mother of 13 has died at just 47 from a deadly case of influenza, prompting a warning from medical experts about a worrying winter surge of the flu.

Victorian woman Julie Theobald was admitted to an intensive care unit in Melbourne on June 10 after her bout of flu worsened and turned into pneumonia.

Jessica Theobald said her mother, who had underlying health conditions, flew in a plane for the first time when she was taken to hospital via medievac. 

She passed away after two weeks in the ICU.  

'We've all been extremely shocked and heartbroken of this news, we could have never imagined losing our mum this early on,' Jessica wrote on GoFundMe. 

'Mum leaves behind 13 amazing children, ageing from seven to 31-years-old and her devoted husband/our Dad, Billy.'

It comes as a senior doctor warned a winter wave of influenza is spiking early this year. 

Warning issued to Aussies over flu - and how to protect yourself

Professor Catherine Bennett, the chair of epidemiology at Deakin University, told Daily Mail Australia that flu patients could be hospitalised even if they were young, fit or healthy. 

'I think everyone probably knows some young, fit, healthy adults who end up in hospital with flu so it's definitely something for everyone to avoid,' she said. 

'If you're with other people that you don't usually hang out with, it's about making sure you try and keep the distance. 

'Be conscious of ventilation, wear a mask if you're in crowded areas, all of those things help protect against these conditions.'

Dr Bennett said a spike in influenza hospitalisations meant Australia could be tipped for a longer flu season this winter. 

'Influenza is still heating up,' she explained. 

'So it looks like Covid might be handing over to influenza in terms of the dominating causes of potentially severe respiratory illness at the moment. 

'The number of people who are coming in to emergency departments is heading towards a crossover where influenza might be in even greater numbers than Covid if you look at the number of people who are being admitted.

'In New South Wales, that number is now approaching 200 a week for influenza and coming down to 200 a week for Covid.'

Dr Bennett said the winter wave of influenza was spiking earlier than in recent years. 

'This year it looks like it's pushed back and the worst is yet to come,' she said. 

'So its a good time to get the message out to people.'

The epidemiologist urged Australians to get an updated flu vaccine.

'Flu vaccines don't last more than six months or so. They're not that different to Covid in respect of the best protection being in the first six months,' she said. 

'It's also the vaccines targeting the variance that you're likely to come across, and that can change year on year. So that's why having an updated flu shot is the most important thing to help reduce the risk.

'It might not stop you from having flu altogether, but it's about avoiding severe illness, and that's what we want, particularly for people with underlying conditions.'

Dr Bennett also recommended wearing a mask in crowded areas, being conscious of ventilation and keeping distance with new people. 

The fundraiser for Julie Theobald has raised $6,000 at time of publication.