According to experts, the Centaurus subvariant of Omicron can evade immunity given by vaccination or prior infection
By Vladislav Strekopytov, RIA Novosti
The original Omicron – BA.1 – appeared in late 2021 in southern Africa. It differed from the previous strains by a huge number of mutations. The spike protein alone, responsible for the penetration of the virus into human cells, had up to thirty mutations.
The super mutant turned out to be mild (it caused a less severe illness), but very contagious, which is why it quickly spread across the globe.
It was immediately followed by BA.2, which was dubbed ‘stealth Omicron’ by the media as PCR tests were unable to detect it and costly genome sequencing had to be used. This variant, even more contagious than BA.1, caused the second ‘Omicron wave.’ In India and South Africa it peaked in December 2021, and in Europe and America it lasted from March to April 2022.
The third wave was related to lineages of stealth Omicron – at the beginning of the year the BA.4 and BA.5 subvariants appeared in South Africa, and BA.2.12 and BA.2.12.1 were dominant in the USA.
In addition to its rapid growth and wide geographical spread, virologists have been alarmed by the huge number of extra mutations in BA.2.75 compared to the original BA.2. Some even suggest considering it a new version of Omicron.
But the World Health Organization (WHO) added the new subvariant to its monitoring list without giving it an official name straight away. An ordinary Twitter user Xabier Ostale made advantage of the situation and on 1st July he wrote: ‘I have just named BA.2.75 variant after a galaxy. Its new name is Centaurus strain.’
Xabier Ostale is not a virologist – he just tweets information about the coronavirus, its strains and ways to stay safe. However, his post quickly went viral, and this nickname stuck to the strain. In the Russian version it sounds as ‘Centaur’, despite the fact that the author named it after the constellation Centaurus.
Thanks to its nickname the world’s leading newspapers (including The Guardian) began to write about the new strain, and people began to search for information on the internet. So a random tweet made one of the Omicron subvariants famous.
By the way, BA.2.75 is not the only variant of SARS-CoV-2 that has recently received an unofficial name. The subvariant BA.5.3.1 is often referred to as ‘Bad Ned’ by virologists because of its N E136D mutation. In Germany it now accounts for more than a quarter of Covid-19 cases.
Everything didn’t go according to the plan
The European Center for Disease Prevention and Control (ECDC), following the WHO, initially classified BA.2.75 as ‘a variant under monitoring’, and on 14th July changed the classification to ‘a variant of interest’. So there are indications that it is more contagious or more severe, but there is as yet little evidence or it is still unavailable.
According to experts, Centaurus has mutations (primarily in the spike protein) that can give it an advantage over other strains of SARS-CoV-2. For example, it can spread faster or evade immunity given by vaccination or prior infection, including the previous Omicron subvariants.
To say anything more definite about the new subvariant scientists need to monitor it for some more time. It is still unclear how widely it will spread. But at least in India it is already causing serious concern among doctors and epidemiologists.
In the middle of last year, many believed that the Delta strain was the pinnacle of the virus’ evolution and the pandemic was nearing its end due to the weakening of SARS-CoV-2 and reaching herd immunity by mankind. But Omicron which easily evades antibodies emerged, and everything didn’t go according to the plan.
A very common one
In terms of symptoms Centaurus is generally similar to all the other Omicron subvariants. Its typical symptoms include a high temperature, cough, a stuffy nose, headaches, muscle pains, a sore throat, stomach aches, diarrhea, nausea and vomiting.
The new variant primarily affects the upper respiratory tract and it is less likely to cause pneumonia. Almost no patients have reported loss of smell so far. According to preliminary findings, it is milder than the other strains of SARS-CoV-2 and causes lower mortality, but it is more transmissible.
The WHO believes that the current increase in the number of confirmed Covid-19 cases around the world is partly due to BA.2.75, and is urging all countries to return to wearing masks and social distancing.
According to the Emergency Response Centre for Preventing the Import and Spread of the Novel Coronavirus, over the past month the number of cases in Moscow has increased more than two and a half times. Covid cases are rising in other regions of Russia as well.