As a cluster of the COVID-19 Delta variant has caused pandemic pandemonium in Sydney - where a strict 14 day lockdown has been implemented - a new strain of the virus is raising more concern among health experts overseas.
In Sydney, the highly contagious Delta variant has seen NSW Premier Gladys Berejiklian say this is "probably the scariest period that New South Wales is going through".
In one week, the Bondi coronavirus cluster grew from nine cases to 110 - a sign of the highly transmissible nature of the virus.
Here's what the different variants mean.
First, what is the Delta variant?
The Delta variant of COVID-19 is a version of the virus first detected in India in October 2020. It's now the globally dominant variant of the disease.
The World Health Organisation designated new names for this and other variants of the virus using the Greek alphabet, from Alpha through to Kappa. The system is designed to prevent stigma, but also reflects the fact that many of the variants have now spread well beyond the country in which they were first detected.
UK data has suggested that Delta is up to 50 per cent more infectious than the Alpha variant, which was previously the most dominant version in the UK. That makes it up to twice as infectious as the original Wuhan-originating version of COVID-19 that was responsible for Australia's second COVID-19 wave in 2020.
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