If COVID has always been 'tricky' - Delta is the ultimate trickster, because when it comes to survival of the fittest it's the mutation that always finds a way to come out on top.
One person infected with the original version of COVID-19 was expected to spread it to two to three people, while a person who has the Delta variant may infect five or six.
The devastating difference between the two strains is very clear.
University of Otago epidemiologist Professor Michael Baker says "it's still transmitted the same way. It just does it better."
"We'd say it's an explosive outbreak that will happen if someone with this virus goes into the community and no precautions are taken."
Sadly, you don't have to look far for real-life examples of that. Delta - which originated in India late last year - ran rampant through the nation.
It moved through the United Kingdom, delaying their June restriction-lifting.
And most recently, it's raced against the New South Wales contact-tracing system and easily won as the speed at which people become infectious is just too quick.
That's why now that we have it here - we're hoping to stop it with a lockdown.
Professor Baker says all of the measures we have put in place for other outbreaks will still work against this strain.
Delta has dominated - but now it's our chance to come out on top.
