Virologists have expressed concern about the emergence of yet another rapidly spreading Omicron variant, which is rapidly gaining ground in India and has already arrived in the UK.
The BA.2.75 variant – nicknamed “Centaurus” – was first discovered in India in early May. Here cases have since risen sharply – and apparently faster than those of the extremely transmissible BA.5 variant, which is also present in India, quickly displacing the previously dominant BA.2 variant in many countries.
BA.2.75 has since also been detected in about 10 other countries, including the UK, US, Australia, Germany and Canada.
The European Center for Disease Prevention and Control (ECDC) labeled it a “variant under monitoring” on July 7, meaning there is some indication that it could be more transmissible or associated with a more serious disease, but it evidence is weak or has not yet been assessed.
The World Health Organization (WHO) is also closely monitoring the new variant, although lead scientist Dr Soumya Swaminathan said there were not yet enough samples to assess its severity.
In addition to its apparent rapid growth and wide geographic distribution, virologists have been warned by the sheer number of additional mutations BA.2.75 contains, compared to BA.2, from which it likely evolved. “This could mean it has had the opportunity to develop an advantage over an already successful virus lineage, said Dr Stephen Griffin, a virologist at the University of Leeds.
“It’s not so much the exact mutations, but the number/combination,” said Dr Tom Peacock, a virologist at Imperial College London, who was the first to identify Omicron as a potential problem in November 2021. “It’s hard to see the effect of so many mutations appearing together – it gives the virus a bit of a ‘wildcard’ trait where the sum of the parts could be worse than the parts individually.
“It is definitely a potential candidate for what comes after BA.5. Failing that, it’s probably the kind of thing we’ve come across next, which is a ‘variant of a variant’.”
Even if it doesn’t take off in other countries, growth in India suggests it will at least be a problem there, Peacock added. “Obviously it’s growing quite well in India, but India doesn’t have a lot of BA.5, and it’s still very unclear how well it’s doing against [that]†
Griffin cited it as yet another example of the virus’ impressive ability to tolerate changes in its spike protein — the part it uses to infect cells and on which most Covid vaccines are based.
“Around this time last year, many were convinced that Delta represented an evolutionary pinnacle for the virus, but the rise of Omicron and the massive increase in antibody variability and evasion is a sign that we as a population cannot follow an influenza-like plan to keep up with viral evolution,” Griffin said.
In addition to vaccines, longer-term plans should also include variant-independent measures to prevent infections and reinfections. “This includes creating infection-proof environments through improved ventilation, filtration or sterilization of indoor air, judicious repurposing of lateral flow testing, and appropriate and assisted isolation periods that will actually reduce continued transmission,” he said.