Last week, the World Health Organisation (WHO) renamed the multiple different strains of Covid-19 circulating around the world to make them easier to understand.
Under the changes, the four most concerning variants take on the first four letters of the Greek alphabet - Alpha, Beta, Gamma and Delta.
Those were previously known as the UK variant, the South African variant, the Brazilian variant and the Indian variant.
Here's a quick guide to some of the variants you're likely to hear about.
Alpha, variant originally detected in the UK
The name of this strain, Alpha, reflects the fact it was the first to be designated a variant of concern by the WHO.
That means it is one of the four variants most concerning to global health authorities because it is believed to show:
- Increased transmissibility or detrimental change in epidemiology
- Increased virulence or change in disease presentation
- Decreased effectiveness of prevention and control measures
It was first detected in September 2020 and was designated a strain of particular concern in December.
It was estimated to be at least 50 percent more transmissible than the first detected strains of Covid-19.
It was behind the UK lockdown in January. However, it is no longer the most dominant strain there - the Delta variant is.
The Alpha strain was also behind a public health response that led to a snap lockdown in Brisbane, Australia earlier this year.
It's been known as the UK variant, the Kent variant and B.1.1.7.
Beta, variant originally detected in South Africa
The Beta variant, originally identified in South Africa, is the oldest of the Covid-19 variants of concern, having been first detected in May 2020, more than a year ago.
It is also known as B.1.351.
According to the US Centres For Disease Control, it shares some of the same mutations as the Alpha strain.
Delta, variant originally detected in India
The Delta variant is the most recently designated variant of concern, as classified by the WHO.
It was first detected in India in October last year, and is considered highly contagious.
UK authorities have estimated it is 40 percent more transmissible than the Alpha variant. It has also been found in some of the cases in Victoria, Australia.
Its other name is B.1.617.2.
Gamma, variant originally detected in travellers from Brazil
This strain, the last of the four listed as a variant of concern by the WHO, was first detected in Japan, in travellers from Brazil.
The strain has raised concerns because it may have been responsible for a surge in cases in Manaus, Brazil, where the population was thought to have reached herd immunity.
The strain is also known as P1 and was first detected in November 2020.
Kappa, variant originally detected in India
The Kappa variant is the one behind most of the cases in Victoria, Australia.
It likely entered the Victorian community via a man who became infected in hotel quarantine in Adelaide before travelling to Victoria.
It was also first detected in India, but unlike the Delta variant it is not listed as a variant of concern.
Instead, the WHO treats it as a variant of interest. However, it is still highly contagious and potentially deadly.
"[It] is starting to show up in places where normally it would be less likely," Victoria's Chief Health Officer Brett Sutton said of the strain.
Its other name, B.1.617.1, is very similar to the Delta variant because they originated from the same strain: B.1.617