The decline - in some cases as much as 50 per cent - has prompted fears that serious illnesses are going unchecked.

Doctor Tim Baker is a specialist emergency physician at the Warrnambool Base Hospital and the director of the Centre for Rural Emergency Medicine at Deakin University Warrnambool.

He said additional doctors and nurses were employed in March when the coronavirus pandemic broke out to prepare for the wave of people expected to turn up at emergency.

Yet strangely, the patients numbers dropped off.

"It was very strange because we increased our capacity to see patients by having extra doctors and equipment, yet we had a large decrease in the number of people attending the emergency department," he said.

"We're not sure yet whether the decrease was due to a real decrease in people becoming unwell, or because there was no weekend sport or sport training to cause injuries and people were distancing themselves from each other so there were less infections like influenza.

"We are also worried people did not attend ED with other conditions that needed treatment either because they were not wanting to put extra burden on hospitals or because they were scared of catching coronavirus in emergency.

In the first months of the pandemic, March, April and May, South West Healthcare saw 2000 more patients than the same time last year, largely due to coronavirus testing through the hospital's respiratory assessment clinic.

However 1000 less patients presented to the emergency department, an 18 per cent decrease from its usual 6000 presentations in that same time period.

"We are concerned that people with other serious problems are staying away because they don't want to be a burden. We would like people to come to the ED as usual though, because we don't want patients to be missing early treatment for heart attacks, strokes, and other serious problems," Dr Baker said.

From March 1 to May 31 this year, Hamilton Base Hospital experienced a significant reduction in emergency department admissions across all triage categories.

Compared to the same period last year, the Hamilton Hospital ED saw a 49 per cent reduction in attendances for non-urgent care, a 20 per cent drop in semi-urgent cases, as well as significant reductions - 15 per cent and 33 per cent - in urgent and emergency cases.

Western District Health Service chief executive Rohan Fitzgerald said similar trends are being seen in hospitals across the state.

"During the COVID-19 pandemic hospitals have experienced a significant drop in ED attendances, which is concerning," he said.

"We want to stress to the community that they should not put off coming to hospital if they need care".

Mr Fitzgerald says the reasons for the lower ED attendances are complex.

"People requiring less urgent care during the pandemic, may be choosing to see how their symptoms play out, or they might be accessing alternative services, such as GP telemedicine.

He said lockdown, social distancing and hand washing guidance has limited social contact, with initial research suggesting that this has led to lower rates of respiratory illness including pneumonia and flu, and fewer exacerbations of asthma and chronic obstructive pulmonary disease.

With schools closed, sporting activities suspended and restrictions to gatherings and recreational activities, the "opportunity" for injury has also dramatically reduced over the last few months.

"We may not fully understand the causes of this widespread reduction in emergency department activity for some time, but want to reassure the community that we are here for them if, and when they need us," Mr Fitzgerald said.

In the first months of the pandemic Portland District Health saw 1300 more patients than the same time last year, primarily through its coronavirus testing sites.

However, 250 less patients presented to the emergency department over that time for other types of problems, a drop of 12 per cent.

Chief executive Chris Giles said their pattern was less clear-cut, seeing an increase in March to a significant drop off in April, then an increase again in May.

"In April we were down almost 50 per cent from 800 in April last year down to 532," she said.

"We've seen less patients presenting with the flu and we think they're either staying away or going to their GP instead.

"When it comes to the serious stuff people need to come to hospital, we don't want people to put it off.

"Everyone should be looking after their primary health needs, we have safeguards in place here and it's business as usual now."

There were 766 presentations in March, up slightly from 721, and a drop off in May to 627 from 727.

It was a similar situation for smaller rural health centres, including Port Fairy and Camperdown hospitals.

Moyne Health chief executive Jackie Kelly said they had a huge decrease in admissions to their urgent care centre and acute services.

They saw just 102 urgent care presentations in March, down from 183 last year, and 20 acute services patients, down from 39 in March 2019.

Camperdown Hospital campus manager Janine Dureau-Finn said they experienced a decline in presentations, with a 50 per cent drop in urgent care patient admissions in April, down from 218 to 107.

March saw a drop from 195 presentations in 2019, to 181, while May saw a slight increase from 288 to 309, which included COVID-19 asymptomatic respiratory screenings.

Hospitals across Victoria recorded a decrease in emergency department presentations during March 2020, the Monash University Accident Research Centre (MUARC) has found.

New figures released by MUARC's Victorian Injury Surveillance Unit (VISU) show there were 151,187 emergency department presentations during March 2020, down from 158,106 in March 2019.

However, there was a significant increase in ED presentations for respiratory and virus-related illnesses. There were 11,078 presentations related to viral infections during the month, compared to 2,871 in March 2019.

Similarly, there were 3467 presentations for upper respiratory infections, a marked increase from the 1,053 presentations a year earlier.

Many other illness categories saw a decrease in ED presentations, including potentially life-threatening conditions.

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