Yesterday Victoria recorded another 725 new coronavirus cases, and its highest daily increase of active cases for the ninth time since the beginning of July.

With the constant news of record breaking case increases, the question remains – when can we expect to see Victoria’s coronavirus cases finally start to decline?

Contract tracing: known vs unknown outbreaks

One of the first things to note when looking at the daily numbers is the contact tracing information. Wednesday’s record breaking increase was made up of a mix of known and unknown outbreaks.

Deputy Chief Health Officer Allen Cheng noted that of the 725 new cases reported, 164 were confirmed to have come from known outbreaks, such as in aged care centres and workplaces.

In areas of cluster (or known) outbreaks, authorities are able to better contain the outbreak and stay informed of where, when and why someone may present with coronavirus symptoms. This is known as contract tracing.

However, when a case arises from community transmission, this tracing is far more difficult to do. The concern here is that the infected person may have been spreading the virus without knowing that they are infected, or that they were ever in an area where infection was a risk.

Speaking on the rate of outbreak infections, Deakin University epidemiology chair Catherine Bennett said, “A lot of the effort over the past few weeks has been suppressing community transmission so that we don’t see big new outbreaks. That is hopefully happening but we won’t see it while we still see outbreaks that have been in train for a number of weeks still causing new cases.”

The current stage-4 restrictions are designed to minimise community transmission and are key in reducing the infection rate in the hopes of getting it down to zero.

Are we doing enough?

This information begs the question, are we doing enough to stop the spread?

It is important to note that as further restrictions are put into place, it will take at least two weeks to see positive results from those interventions, given the time it takes between contracting the virus, showing symptoms, getting tested and receiving results.

Already, in the last few weeks since the mandatory mask mandate, there have been some positive results. Daily reports of new cases have not been rising as steadily, and we have seen days with far fewer cases and just a handful of record days.

While we can’t ignore that COVID-19 infections are still rising, the fact that we’re not seeing a consistent increase should give hope that the interventions are starting to work.

What is the R value and why is it important?

The issue that we are still battling is the rate of reproduction (known as the “R value”), a measure of how an infectious disease is spreading.

When the R value is at two, it tells us that a single person with coronavirus will infect two people. This means that every week or so the number of active cases will double, as those who came into contact with the infectious person receive their positive diagnosis. Getting the reproductive factor below one is when we will see the infection rate begin to slow.

We have seen a decline in the reproductive factor. At the beginning of July it sat at 1.75 and at the end of July it was at 1.16. While the infection rate is still high, it is not doubling or tripling like it was at risk of doing in the early days of the June/July outbreak.

Burnet Institute deputy director and infectious diseases physician Margaret Hellard explained that with the R value sitting at 1.16, if 10 people are infected, they will pass it on to 11 or 12 people, rather than the 17 or 18 people being infected when the value sat at 1.75. As far as the current state in Victoria is concerned, this means that when there are 500 active cases, we can expect to see around 580 additional cases about a week or so later.

“For this week it is not surprising that we will have the same number of cases, if not 10 per cent more cases, because of the R value being what it is,” Professor Hellard said.

“Hopefully in a week or two weeks the R value will fall below one and we will see a decline in the number of cases each day after that.

“If we are to get that R value to get down and stay down, we need community co-operation, this is not just about a government bringing in a restriction measure it is about the community engaging in the response,” Professor Hellard said.

So when?

It has been exactly two weeks since the mask mandate. The hope is that with the new stage four restrictions coming into effect, along with harsher crackdowns on the movements of workers, we will begin to see a decrease in infection numbers in the next two to three weeks.

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