Tests for August 11-17 were almost 17 per cent down on the previous seven-day period and that has authorities worried they could lose the true picture of how the state's second outbreak is progressing.

People are being urged to go for tests no matter how mild their symptoms.

The call came as Victoria had 222 new cases on Tuesday, its lowest daily total in a month.

While Tuesday's 17 deaths also showed the crisis is far from over, the plummeting case numbers prove the lockdown measures are working.

Melbourne is in the third week of a strict level-four lockdown due to end on September 13 and the rest of Victoria is under level-three restrictions.

Premier Daniel Andrews said there was little doubt that the stage-four provisions were contributing to lower test numbers, given people were more restricted in their movements.

But he noted there were no restrictions on people going for virus tests.

"I don't want a situation where we see numbers continue to fall but at the same time the total number of tests falling also because that will mean we don't have confidence that we have an accurate picture of how much virus is in the community," Mr Andrews said.

"We don't want that to be an inhibitor in any way of moving to a new phase and a new set of rules.

"We have to have that confidence that we are getting a complete or as close to a complete picture as we possibly can."

Given flu cases are also down by 75 per cent on this time last year, the advice is that a sore throat or cough is more likely to be coronavirus.

It prompted a blunt description from Victorian chief health officer Brett Sutton about potential early coronavirus symptoms.

"It doesn't have to be days and days of a cough ... it doesn't have to be yellow or green sputum or snot," he said.

"It can be the very mildest of flu or cold-like symptoms."

But the dramatic drop in new case numbers - the lowest since 217 on July 18 - also has Prof Sutton more bullish about the immediate future.

"I would hope we are in the hundreds, not in the 200s, next week but it all depends on everyone doing the right thing," he said.

Tuesday's deaths take the state toll to 351 and national figure to 438.

They included a man in his 60s, a woman and a man in their 70s, two women and four men in their 80s and four men and four women in their 90s.

All but four are linked to aged care outbreaks, with 230 total deaths in that sector.

Aged care numbers are holding steady - 2024 actives cases and 120 active outbreaks.

There are 7274 active cases in Victoria, a drop of 200 on Monday, and active regional cases also fell from 436 to 422.

So-called "mystery" cases remain high at 3669 but that is only an increase of 43.

Experts warn the death toll will remain significant for several days, given there is always a lag of a couple of weeks after the peak of coronavirus outbreaks before fatalities decline.

The state had 25 fatalities on Monday, an Australian record.

Victoria hit a record 725 new cases on August 5 but there have been no 400-plus days since last Wednesday.

Australian Associated Press