Earlier than Australia’s latest adjustments to COVID testing, figuring out after we reached the height of circumstances was, in principal, simple.
We appeared on the numbers of recent day by day circumstances, identified by way of PCR. From there, we labored out a spread of different key indicators associated to COVID unfold, testing and hospitalisation – every depending on these day by day case numbers.
Nonetheless, we’ve seen an enormous spike in circumstances just lately as individuals check constructive utilizing fast antigen assessments, particularly as reporting their outcomes to state well being authorities is now doable and turning into obligatory.
So will probably be just a few days earlier than we will measure some key numbers with any diploma of accuracy. Solely then will be capable to say with confidence after we’ve hit the height and are coming down the opposite facet.
1. The variety of new day by day circumstances
Most individuals by now would have seen an epidemic curve. It’s a plot of the variety of new circumstances of COVID-19 identified every day. Right here is the present epidemic curve for New South Wales.
Creator supplied/Adrian Esterman
As for the date, states and territories use completely different cut-off occasions for outlining a 24-hour interval. As authorities undertake investigations, the date of some circumstances can change. So, will we plot the day by day introduced case numbers, or the “true” case quantity after modifications?
That sounds sophisticated, however much more sophisticated is attempting to outline a case.
Earlier than fast antigen assessments grew to become out there to the general public to be used at dwelling, circumstances had been identified from constructive PCR assessments.
Then, due to big queues at PCR testing hubs and many individuals, even these with signs, giving up and never getting examined, our testing system modified.
Nationwide Cupboard agreed to take away the requirement for a PCR check to verify a constructive fast antigen check end result.
As most states and territories transfer in direction of reporting each constructive PCR assessments and constructive fast antigen assessments, we nonetheless have to iron out the bumps within the information. Doubtlessly, somebody may get each assessments and be included twice!
The uncertainty in case numbers additionally impacts different key parameters we use to watch the present wave.
2. The Reff
The efficient replica quantity (Reff) is a measure of what number of different individuals on common every case infects. We would like that to get under 1 to cease an outbreak. At its simplest, the Reff is as we speak’s case quantity, divided by the case quantity 4 days in the past.
Since we at the moment have so many issues defining and counting case numbers, will probably be just a few days earlier than we will persistently interpret the Reff for every state and territory once more.
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3. Proportion of constructive assessments
That is the share of constructive assessments out of all COVID-19 assessments taken. It is a crucial measure because it offers a sign of the quantity of undiagnosed circumstances locally.
The World Well being Group suggests whether it is below 5%, issues are below management.
When analysis was solely by PCR check, we had good information on each the variety of assessments, and the quantity that had been constructive.
Now, states and territories are shifting to reporting fast antigen check outcomes, it’s not so simple.
Some jurisdictions like Queensland solely ask you to report a constructive end result. This implies we now not know what number of assessments had been taken. SA Well being is encouraging individuals to report detrimental assessments as nicely, which is a a lot better system.
4. Quantity hospitalised
As Australia opens up, we’ve been instructed to pay extra consideration to COVID-19 hospitalisations, moderately than simply the case numbers. However even that will get sophisticated.
Clearly if somebody assessments constructive for COVID-19 after which will get admitted to hospital, they’re an admitted case. However what if they’re admitted as a possible case?
And will hospitalisation numbers embrace individuals being managed in a hospital-in-the-home kind association? In any case, they nonetheless take up hospital sources.
Lastly, what in the event that they had been admitted for one thing else however subsequently identified with COVID-19 in hospital?
Much more troublesome is trying to calculate the speed of COVID-19 hospitalisation. That is the variety of individuals in hospital with COVID-19 divided by the variety of individuals identified. However you need to resolve which period durations you’re speaking about, one other debate totally.
There are comparable points with measuring the quantity and charges of individuals in intensive care.
We’re seeing extra COVID sufferers in ICU as case numbers rise. That impacts the entire hospital
How do these adjustments impression modelling?
NSW Well being just lately launched modelling to take a look at what’s forward.
With present restrictions in place in NSW, the modelling exhibits a peak of 4,700 hospitalisations, with 273 in intensive care over mid- to late January.
It’s unclear whether or not adjustments to testing guidelines have been factored into the modelling. Nonetheless, it’s understood, even when the detection fee adjustments considerably, it doesn’t have an effect on any projection of when the height shall be reached that a lot.
Modelling is subsequently nonetheless more likely to be moderately correct regardless of the adjustments to COVID testing. That is excellent news for different states and territories that depend on modelling outcomes for planning.
Scientific modelling is steering our response to coronavirus. However what’s scientific modelling?
The place to from right here?
A superb begin could be to have obligatory reporting of fast antigen check outcomes, each constructive and detrimental. That means we will calculate the share of constructive assessments once more.
The UK has a superb system. After you’re taking a fast antigen check there, you scan a QR code on the pack and report the check outcomes as constructive, detrimental or void to a central authorities database.
Importantly, let’s have one nationwide physique accountable for defining, gathering and reporting COVID-19 statistics. It may very well be the Australian Institute of Well being and Welfare. Higher nonetheless could be to have our personal Centre for Illness Management, which individuals like myself have been calling for for a very long time.
Chris Billington, from the College of Melbourne, contributed to the part on modelling.
Adrian Esterman doesn’t work for, seek the advice of, personal shares in or obtain funding from any firm or organisation that might profit from this text, and has disclosed no related affiliations past their tutorial appointment.