Since the COVID-19 pandemic first began, many have become desensitised to these next few words:
There's a new Omicron subvariant.
BA.2.75 was first detected in India in early May. Since then, it's been found in Europe and the United States.
The chief scientist with the World Health Organization (WHO), Soumya Swaminathan, said BA.2.75 appeared to have mutated in a way that could indicate "major immune escape".
However, Dr Swaminathan says there isn't enough data to know how severe its impact will be.
Here's what we know so far:
What is the BA.2.75 subvariant?
Adelaide epidemiologist Adrian Esterman says it's "another child of BA.2".
"The fact is, there's no research that shows BA.2.75 is more transmissible or more serious," Professor Esterman said.
In a video posted to the WHO's Twitter account, Dr Swaminathan said BA.2.75 had "not yet officially been named", but that some people were "referring to it as BA.2.75".
"There are still limited sequences available to analyse, but this subvariant seems to have a few mutations on the receptor binding domain of the spike protein, a key part of the virus that attaches itself to the human receptor," she said.
"We don't know that. So, we will have to wait and see."
Dr Swaminathan said the WHO committee and the Technical Advisory Group on Virus Evolution (TAGVE) are "constantly looking at the data from around the world".
Why are some people calling BA.2.75 'Centaurus'? Is this official?
Ah, Twitter. Some people have been calling the new variant 'Centaurus', after the Greek father of the mythical Centaurs.
While a catchy name, it's not official. A Twitter user, Xabier Ostale, who is not a virologist, coined the nickname in a tweet.
"If you can do that, you may as well call BA.4 and BA.5 Gemini — the naughty twins."
Should we be worried?
Professor Esterman says that, until more substantive research is done, BA.2.75 remains a variant that is being monitored.
"We simply don't know if it's more transmissible or severe at this stage. If we find that it is, then it will become a variant of concern."
How are the names of subvariants decided?
Professor Esterman said the original variants of the Sars-CoV-2 virus, which causes COVID-19 infections, were named after the country where they were first discovered.
However, the WHO decided that this wasn't fair on the countries involved.
"Even though it might first be discovered in Brazil, it may have actually started in Colombia," Professor Esterman explained.
"So they decided these names stigmatise the countries too much."
Instead, the WHO began to name variants after letters of the Greek alphabet.
"We had Alpha, Beta, Gamma, Delta and so on," he said.
How did it all start? BA.1, BA.2 and BA.3
Omicron was first identified in late November in South Africa. Since then, it has evolved into a family tree, one that keeps growing.
It started off as three subvariants, all appearing in late November 2021 in southern Africa: BA.1, BA.2, and BA.3.
Professor Esterman said all three of these were discovered roughly around the same time, in Botswana.
"BA.1 initially took over in Australia and had a massive number of cases. At its peak, we were getting 100,000 cases a day."
Professor Esterman said BA.2 turned out to be more infectious than BA.1, eventually overtaking it.
As for BA.3 — it never really took off.
"Some of the mutations made BA.3 less transmissible. So it pretty much died out," Professor Esterman said.
"What's happened now is that BA.2 has now had children – think of them as grandchildren [of COVID-19]," he said.
Their names? BA.5, BA.4, BA.2.1.2.1 and BA.2.75
When were BA.4 and BA.5 detected?
BA.4 was first detected in January 2022 in South Africa. BA.5 was also detected in South Africa, in February 2022.
"These two are talked about together because they have almost identical mutations," Professor Esterman said.
However, they do differ in some of the mutations on the body of the virus.
"It turns out BA.5 is more infectious than BA.4. [The] majority of the cases in Australia are either of these two."
