“Centaurus”: virologists express concern over new Covid subvariant | Coronavirus
Virologists have expressed concern over the emergence of another fast-spreading Omicron variant, which is rapidly gaining traction in India and has already arrived in the UK.
The BA.2.75 variant – nicknamed “Centaurus” – was first detected in India in early May. Cases here have since risen sharply – and apparently faster than those of the extremely transmissible BA.5 variant, which is also present in India, and is rapidly replacing the previously dominant BA.2 variant in many countries.
BA.2.75 has also since been detected in a dozen other countries, including the UK, US, Australia, Germany and Canada.
The European Center for Disease Prevention and Control (ECDC) designated it a ‘monitored variant’ on July 7, meaning there are indications it could be more transmissible or associated with disease more serious, but the evidence is weak or has not yet been assessed.
The World Health Organization (WHO) is also closely monitoring the new variant, although its chief scientist, Dr Soumya Swaminathan, said there were not yet enough samples to assess its severity.
In addition to its apparent rapid growth and wide geographical distribution, virologists have been attracted by the number of additional mutations that BA.2.75 contains, compared to BA.2, from which it is likely to have evolved. “It could mean he was lucky enough to develop an advantage over an already successful viral line, said Dr Stephen Griffin, a virologist at the University of Leeds.
“It’s not so much the exact mutations, but rather the number/combination,” said Dr Tom Peacock, a virologist at Imperial College London, who first identified Omicron as a potential problem in November 2021. “It’s hard to predict the effect of so many mutations appearing together – it gives the virus a bit of a ‘generic’ property where the sum of the parts could be worse than the parts individually.
“It’s definitely a potential candidate for what comes after BA.5. Failing that, it’s probably the kind of thing we’ll have found next, i.e. a ‘variant variant’.
Even if it doesn’t take off in other countries, its growth in India suggests there will likely be a problem there, at the very least, Peacock added. “He’s clearly developing quite well in India, but India doesn’t have a lot of BA.5s, and it’s still very unclear how well he’s doing against [that].”
Griffin cited it as 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.
“At this time last year, many were convinced that Delta represented an evolutionary peak for the virus, but the emergence of Omicron and the large increase in antibody variability and avoidance is a sign that we cannot not, as a population, follow a flu-like plan to keep pace with viral evolution,” Griffin said.
In addition to vaccines, longer-term plans should include variant-agnostic measures to prevent infections and reinfections. “This includes creating infection-resistant environments through improved ventilation, filtration or sterilization of indoor air, sensitive new provision of lateral flow testing, and appropriate and supported periods of isolation that will reduce actually the ongoing transmission,” he said.