Thread by @MackayIM

😷Australia National #Flu graph just out, up to 22MAY22.
🦠Early
🦠Steep
🦠Lots
🦠All over

To clarify again this fortnight.
Yes, there is undoubtedly more testing capacity in Aus after labs beefed up for the pandemic.
So how do we know this rise is real, & not just boffins getting bored with testing for SC2 & switching to flu virus testing? (LOL)

One approach to check this is a real rise in flu cases, not just over-testing is look at deaths, hospital beds, ICU beds with flu-confirmed patients.
🛏️there have been 3 lab-confirmed influenza deaths (+3 since last fortnight)
🛏️386 hospital admissions (+233)
🥽28 in ICU (+21)

Another way is to look at the proportion of tests that are virus-positive (=positives divided by total tested).
🧬in this last report, broken down by age, the rate is highest at about 400 per 100,000 population.

For context, at about this time in 2019 which was an early starting & huge flu year in Aus, the rate was about the same. In 2017, also a huge but shorter #flunami (see the initial graph), the rate was much lower (that seasons took off later than average).

If we look at the proportion of respiratory virus tests that are influenza-positive at special "sentinel" labs, we can see the rate has been building (not sure what the denominator was in Jan-early Mar) and has spiked lately.

This is definitely an early flu season. Total numbers can be misleading. Test positivity rates aren't as high as in the same period in 2019 but are higher than in the same period in 2017 or 2016. Hospitalisation & ICU numbers are almost identical to 2019 but above 2017 & 2016.