Alert after detection of Centaurus, the new subvariant of coronavirus, even more contagious
Amid the spread of the BA.4 and BA.5 Omicron variants, the SARS-Cov-2 virus continues to change. Now, experts are warning of a new sublineage of Omicron, known as BA.2.75 or centaurus, which could exhibit increased transmission capacity.
It was first detected in a sequence taken in India in early June, but has already spread to eight other countries: Japan, Germany, the United Kingdom, Canada, the United States, Australia and New Zealand.
BA.2.75 is a “second-generation” subvariant derived from BA.2 that records, according to Indian scientists, an 18 percent growth advantage over other Omicron sublineages. It includes new mutations in the spike protein, in addition to mutations already present in Omicron.
Of most concern are ‘G446S’ and ‘R493Q’, as they give the variant the ability to evade antibodies. This allows it to infect people who have been vaccinated or previously infected.
Also warning against BA.2.75, the Fred Hutch Research Institute’s Bloom lab tweeted that the variant is “worthy of monitoring” due to the “appreciable antigenic shift” compared to its parent, BA.2.
The subvariant has 45 mutations in common with BA.5 and 15 are unique. Among these, 8 mutations in the Spike protein stand out. G446S is a mutation that could help the virus escape the antibodies elicited by current vaccines, which “remain effective against BA.2″. However, “it would have a lesser effect on antibodies in people with a previous infection produced by BA.1. Therefore, the antigenic advantage of BA.2.75 relative to BA.2 will be more pronounced in people who have not been exposed to BA.1″, the laboratory explains.
The R493Q mutation, meanwhile, appears to increase the virus’s ability to bind to ACE2, the protein that the coronavirus uses to enter cells.
So far, there is no evidence to suggest that BA.2.75 leads to a more severe form of infection, but there is concern about its ability to transmit because of its rapid spread in India. In just 5 days, the new subvariant accounts for 18 percent of the total samples tested. In addition, experts claim that it could be behind the recent increase in Covid-19 cases in the country. In the last 10 days, the number of new cases in the country has ranged from 15,000 to 19,000, while the number in recent months remained below 3,000.
The New Zealand Ministry of Health, which first detected the variant last Friday, says the new sublineage “has some features that appear to enhance its ability to evade immunity, similar to BA.4 and BA.5 subvariants, and there is some preliminary overseas evidence that it may be more transmissible than BA.2. There is no current evidence that it leads to more severe disease, although evaluation of the evidence is at a very early stage.”
For his part, Shay Fleishon of the Central Virology Laboratory at Sheba Medical Center in Tel Hashomer, Israel, called the new subvariant “alarming” and stressed that while it is too early to tell whether it will be the next dominant variant, “it could imply a future trend.”
The expert explained in a Twitter thread that in recent months a trend of Omicron lineage-based variants with mutations in the S1 section of the spike protein, and specifically in the part of the spike protein that the virus uses to connect and enter cells, has been observed “at a level that had not been seen in second-generation variants.”
Moreover, until now, these second-generation variants had only been found in a few cases within a region. “This is the first time that a second-generation variant of Omicron has spread to multiple regions,” concludes the Israeli medical expert.