Note: These charts are all updated once per day, typically about 4pm in the afternoon when the Victorian health department releases the detailed daily figures.
The increase in case numbers
This graph shows the net daily increase in coronavirus cases in Victoria since March. That means, for each day, the number of fresh cases that have been recorded statewide.
The daily net increase is not the same as the number of new daily cases, because sometimes raw case numbers get revised down a day or so later. It might turn out a test was wrong and gave a positive result to someone who didn’t actually have coronavirus (this is called a false positive) or that someone has been counted twice in the data by mistake. On July 8, for example, there were 134 new cases but 16 previous cases were removed from the tally, meaning the net increase was 118.
I’ve chosen to display this chart rather than the number of new daily cases, because it adjusts for the inaccuracies caused by false positives and any double counting. A graph of the number of new coronavirus cases per day in Victoria can be found here.
The number of active coronavirus cases in Victoria
There have been about 9000 confirmed coronavirus cases in Victoria as of July 9, but many of those were recorded in earlier months, so this number doesn’t tell us how many people are currently infected with COVID-19.
For that reason, we talk about active cases when trying to get a sense of the current number of people infected. Active cases are people who tested positive for coronavirus for recent days who have not yet recovered.
This graph shows the running total for the number of active cases over the past few months:
The first peak in the chart is from the steep rise in cases in late March, when coronavirus started spreading rapidly through the western world.
During April, active case numbers were brought down – pretty much every day that month the number of new infections was being outweighed by all the people making a full recovery from the virus.
That mound in the graph during May is largely because of an outbreak at a meat processing plant in Melbourne’s west, which ended up leading to more than 100 infections.
As we enter early July, there are now more active cases in Victoria than at any stage since the pandemic started. It’s too early to say what the shape of the data will be going forward.
You can also view how active case numbers in each local government area have changed since June using the graph below. Simply choose your area from the drop-down menu.
There’s one thing I ought to mention about this local government area-level data – it shows the typical area of residence of the infected person, which is not necessarily where they contracted the virus or where they are currently located.
For some areas you might notice irregular wobbles in the number of active coronavirus cases on the map or on the graphs – this is likely because of false-positive diagnoses being removed from the tally after a day or so.
The source of infection of coronavirus cases
During March and April, most new coronavirus infections confirmed in Victoria were in people returning from overseas who had tested positive while being held in hotel quarantine. But during June and July, virtually all of the new cases are being picked up within Australia.
This graph compares, side by side, the number of infections detected in overseas travellers in hotel quarantine against the number of people who contracted the virus locally:
There are two types of local infections: those that have a known source (someone might test positive for coronavirus and then their family members, close friends or housemates catch the virus a few days later) or tied to a known outbreak, and those for which the source is unknown.
The most worrying types of coronavirus cases are those with an unknown (sometimes called community transmission), because that suggests the virus is circulating within the community. These graphs break down the source of local transmission of coronavirus in Victoria. As you can see, community transmission has been on the rise.
Now, looking at these graphs, you might be wondering why the data stops suddenly almost a week ago. That’s because it takes the health department several days to determine the source of infection, so most of the new cases are still being investigated.
I’ve only included days for which the bulk of infection sources have been worked out, otherwise a cursory reading of the data could imply infection numbers are trending down when they are not.
The graphs above need a bit of explanation, so we usually include this simpler one to show the running total for community transmission:
But whenever you see this graph, keep in mind that whenever there is an increase in community transmission it’s usually because cases from up to a week ago have been investigated.
Hospitalisations because of coronavirus in Victoria
This graph shows the number of people who have been hospitalised in Victoria because of coronavirus:
The number of hospitalisations tends to lag behind any increase in new cases as complications typically arise from coronavirus at least one week into the infection.
How Victoria compares with other states
This graph shows how Victoria compares with NSW when it comes to the number of cases confirmed per day:
As of July 9, there had been 22 deaths from coronavirus in Victoria and 49 in NSW.
This graph shows how Victoria compares with the state of Indiana, in the US. Both states have a similar population, of about 6.5 million.
As of July 7, there had been 2717 deaths from coronavirus in Indiana, according to data compiled by Johns Hopkins University.
If you have any questions about Victoria’s coronavirus data, the way it has been presented or its interpretation, send me an email at email@example.com or leave a comment on this article (I will do my best to reply to comments).
Craig Butt joined The Age in 2011 and specialises in data-driven journalism.