The arrival of the Delta variant really was a massive curveball that few experts saw coming.
It ripped through populations overseas and quickly punched holes in Fortress Australia.
It especially challenged our public health response with its incredible infectiousness and has taken hold in NSW, Victoria and ACT.
But how did Delta come into existence in the first place? And as more and more of us are vaccinated, what might come next as the SARS-CoV-2 virus continues to evolve?
On today's Coronacast, a very special guest explains all.
GUEST:
* University of Sydney evolutionary biologist Professor Eddie Holmes