Key Points
- The latest subvariant of the Omicron strain of COVID - dubbed BA.2.75 - has arrived in Australia.
- The World Health Organization (WHO) announced it was closely monitoring this variant in early July.
The latest subvariant of the Omicron strain of COVID - dubbed BA.2.75 - has arrived in Australia, along with talk of escaping immunity, increased transmissibility and reduced coronavirus data.
While initial reports suggested that this new mutation of COVID-19 appears to be highly contagious, BA.2.75 still represents a small number of cases in Australia.
As of 18 July, the federal Department of Health has recorded at least 10 cases of BA.2.75.
A spokesperson for the department said: “Whilst there are suggestions that the BA.2.75 variant is more transmissible than earlier Omicron strains, at this stage there is no clear evidence that it is more severe.”
A global perspective
The World Health Organization (WHO) announced it was closely monitoring this variant in early July.
After emerging in India in May, the subvariant has been found in countries including the United States, Britain, Germany and most recently, the Netherlands.
A nurse prepares to give a COVID vaccine to a man at a clinic in India. Source: AAP / Anupam Nath/AP
She admitted tracking and analysing newer variants was becoming more difficult, meaning there is less available information on BA.2.75.
Dr Van Kerkhove said data from around the world identifying such characteristics is becoming increasingly limited.
She said despite an increase in reported cases globally in recent weeks “surveillance activities have declined drastically around the world including testing.”
“At the present time we have very few sequences of this particular sublineage that are available publicly but we are concerned about this sublineage,” Dr Van Kerkhove said.
She said every variant of COVID is a concern for the WHO “because this virus is circulating at such an intense level globally,” and WHO considers all Omicron subvariants to be "variants of concern".
The COVID family tree
Like, BA.4 and BA.5, BA.2.75 is a mutation of the Omicron strain which was first identified in November 2021.
Professor Cassandra Berry, a professor of immunology at Murdoch University, said BA.2.75 came after BA.4 and BA.5 in terms of chronological order.
“It's more closely aligned with the BA.2 variant, it's like a branch out from there,” she said.
What’s in a name?
While some have referred to the subvariant as “Centaurus” — the name of both a faraway galaxy and a Greek mythological character, the WHO simply lists it as BA.2.75, a subvariant of the Omicron variant.
The Centaurus moniker appears to have been suggested by an individual on Twitter who often tweets content about COVID, and others picked it up and ran with it.
Immune escape
Professor Barry said one of the concerns around BA.2.75 and any future variants that emerge is whether these variants can work around people’s existing immunity.
“A lot of people now … they’ve been vaccinated, or they may have had COVID, and survived, recovered, then if the virus changes as a mutation, and the immunity doesn't work, that's what we call immune escape.
“So if your antibodies were made to a little area on the tip of the spike protein on the outside of the virus, that no longer could recognise this mutation, the variant has escaped that antibody, so the antibody is useless, even though we've got bucket-loads of it in our bloodstream, it can't find the virus, it can't stick to it, it can't block the virus from replicating.”
Professor Berry said this was why some people were contracting COVID more than once.
Cassandra Berry is an Immunology Professor at Murdoch University. Source: Supplied / Cassandra Berry
“If we get another dose of the vaccine, it just re-stimulates our immune system so that our B cells will make more antibody. And even though the antibody might not be specifically matched to this particular mutated virus, this BA.2.75 variant, there still will be some cross-reactive antibody that should be able to just hold it at bay,” she said.
A different type of vaccine
Professor Berry believes a “universal” or “neutral” vaccine could provide more widespread, effective protection against people getting coronavirus.
“The cleverest thing, I believe, is to get some common antigen from all the variants that they share, part of the virus that the variants don't mutate,” she said.
“If we could find a shared region of the spike between different variants, and that's usually at the base rather than the tip spike, that it is difficult to make a strong vaccine and antibody response to a shared region of the spine.”
Future variants
Professor Berry said it was not possible to predict whether BA.2.75 would become the dominant strain of COVID-19 in Australia.
She said the spread of viruses was very much about “survival of the fittest”.
“The fittest virus will be one that can reach more people and replicate at a higher level, so it's kind of by default, evolving to be a very highly transmissible, dominant strain,” she said.
“If it kills more people and becomes more virulent, it's not a very clever virus because then it could just vanish, like some of the Ebola outbreaks that we've had.”
Professor Berry said while she’s not sure COVID variants will make their way to the end of the Greek alphabet, the virus is not going anywhere soon.
“I don't think we'll get all the way to Omega, but I do think we'll have to live with COVID every year, until we have really strong immunity and a very broad cross-reactive immunity by our new generation vaccines,” she said.
Professor Berry said she encouraged people to wear masks when they leave their house as a way to reduce the spread of COVID.
“I think the mask-wearing would really reduce the risk of it being transmissible, and keep those case numbers at bay,” she said.
