BA.2.75, which has picked up the nickname "Centaurus," is now dominant in India, overtaking the previously most transmissible subvariant BA.5.
A new subvariant of Omicron is making headlines around the world, with health agencies and virologists believing it could likely become the dominant strain in the ongoing coronavirus pandemic.
BA.2.75 is already becoming dominant in India, after it was first detected there in May.The subvariant has now been found in dozens of countries including the UK, Germany, and the Netherlands.
Because it is overtaking the previously dominant strain in India - BA.5 - virologists think it is likely to be more transmissible and therefore likely to become dominant elsewhere. But they caution that they don’t yet have enough data on the strain to make definitive statements like this.
The Dutch Institute for Public Health announced this week that BA.2.75 had been identified in the Netherlands, saying little is known about it, although “it appears to be able to more easily bypass the defence built against the SARS-CoV-2 coronavirus through small, specific changes".
This raises fears that it could potentially be adept at evading immunity built up through vaccination or previous COVID-19 infection.
“We're seeing this new variant displacing all the variants that we have considered previously to be extremely transmissible, yet we don't know quite why this variant is becoming so dominant yet,” Dr Eleanor Gaunt, a virologist at the University of Edinburgh, told Euronews Next.
She said BA.2.75 “could be able to get around previously existing immunity, or it could be that it's better at transmitting,” but that given the lack of data, “only time will tell”.
BA.2.75 has picked up the moniker “Centaurus”, although it hasn’t received an official Greek letter from the World Health Organization yet, with the WHO insisting it is a subvariant of Omicron.
The name Centaurus seems to have stemmed from a tweet by user @xabitron1, who wrote on July 1: “I have just named BA.2.75 variant after a galaxy. Its new name is Centaurus strain. Get used to it. Today, I'm in command of anything pandemic.”
This origin story has been confirmed by the fact-checking website Snopes.
What is different about ‘Centaurus’?
BA.2.75, like BA.5, is a subvariant of Omicron, the highly transmissible form of coronavirus that quickly became dominant around the world this year.
Experts say the fact it is now overtaking BA.5 in India suggests it could become dominant elsewhere.
“What we're seeing with this new BA.2.75 is that it is spreading in countries where there have been high levels of vaccination, so it does seem that this virus is able to get around some of the pre-existing immunity,” said Gaunt.
This could be due to the number of changes in its spike protein – the protein on the surface of a virus that helps it to enter cells.
“That's the part of the virus that your immune system recognises,” said Gaunt.
“And so as it changes what it looks like, then your immune system is less able to recognise it. It's certainly something that's happening here”.
While it is possible BA.2.75 will become dominant around the world, it’s not necessarily something to worry about too much, according to Gaunt.
“This is a pattern of behaviour that we've seen multiple times in this pandemic. We get a new variant that is more transmissible and it displaces an older variant, but people at the population level are getting more immunity from exposure to the virus and through vaccination,” she said.
“And we're seeing the clinical severity of hospitalisations associated with coronavirus in general decreasing. So it's not necessarily something to be alarmed about”.
Risk of reinfections
Gaunt says there is anecdotal evidence with most of the Omicron subvariants that people can become reinfected with coronavirus shortly after a previous infection.
But she points out that we are currently in a period of the pandemic where COVID-19 is circulating relatively freely in the population.
“The chances of the virus spreading are more likely than they were, say, a year ago or two years ago”, she said, when for example there were mask mandates and more restrictions in place in many countries. “So again it’s not necessarily something to be alarmed about,” she said.
“If you are seeing reinfections, the likelihood is that reinfections will be clinically less severe. This virus isn't going anywhere. People are going to be reinfected”.
Will COVID ever end?
Gaunt advises, like almost all virologists and experts studying COVID-19, to get vaccinated if you can.
New vaccines specifically targeting Omicron are likely to be coming out soon, and getting that vaccine will reduce the risks around COVID, she adds.
And in terms of the longerterm picture for the pandemic, Gaunt says it seems likely to fall into a pattern similar to that of the common cold, where it reaches “a kind of equilibrium with humans”.
“So we get infected, we get a mild infection, and we get repeated infections throughout life. And that is the long term prognosis for the SARS-CoV-2”.
Other experts agree that vaccines and boosters are still the best defence against severe COVID-19, even if they can’t guarantee reinfections won’t occur.
“The current subvariants are a bit further away from ancestral strain in terms of immunity they will elicit, so vaccines are not quite so good at preventing infection with these more recent strains,”Dr Mike Ryan, the WHO’s emergencies director, told a media briefing this week.
Dr Maria Van Kerkhove, WHO’s technical lead on COVID-19, added that BA.5 is “the most transmissible variant we have seen”, and warned the next variant she talks about would therefore be “even more transmissible than the last”.
The emergence of BA.2.75, she said, “tells us we will continue to see repeated waves of infection”, but both experts are clear on how to avoid rising rates of hospitalisations and deaths as COVID spreads: Get vaccinated.