The UK has said that another sub-strain of the Omicron variant of Covid has been emerged in more than 40 countries across the world which can escape even the RT-PCR test. The BA.2 sub-strain, normally called the “stealth Omicron”, has caused fears of a stronger wave across Europe.
As indicated by the World Health Organization, the Omicron variation has three sub-strains – – BA.1, BA.2, and BA.3. While the BA.1 sub-strain is predominant among the Omicron cases registered in the world, the BA.2 sub-strain is spreading rapidly.
Denmark on January 20 reported that the BA.2 sub-strain represents close to half of the country’s active cases.
The UK health officials have assigned BA.2 as a “variant under investigation”, which is an antecedent to a strain being proclaimed as a “variant of concern”.
Along with UK and Denmark, cases of BA.2 sub-strain have been identified in Sweden, Norway, and India. Researchers in India and France have even cautioned with regards to the sub-strain, dreading it may dominate the BA.1 sub-strain.
The UK had found 53 sequences of the BA.2 sub-lineage as of January 10, with latest figures due to be published later on Friday.
Research says that, even as the BA.2 sub-strain imparts 32 strains to BA.1, there might be in excess of 28 unique mutations to it, a report in Fortune read.
Researchers say that BA.1 has a mutation – the cancellation in the “S” or spike quality – that appears on PCR tests, making the recognition of Omicron simple. BA.2, then again, doesn’t have a similar mutation which makes hard to recognize.
“However, the BA.2 sublineage lacks this deletion in the spike so that it can be picked by the use of most of the PCR kits being in use for the RT-PCR tests. This new sublineage BA.2 is called ‘stealth Omicron’ because it lacks the deletion that allows it to be picked up by PCR tests. BA.2 appears to be the major Omicron lineage in parts of India and the Philippines and there is evidence it is growing compared to BA.1 in Denmark, the UK and Germany,” told Prof Sunit K Singh.
While the BA.1 sub-strain might get away from RT-PCR tests sometimes, specialists say these tests are as yet the best quality level in recognizing the infection. “Lab RT-PCR test is the gold standard test and there is no difference in the sensitivity or pick-up rate between Omicron or the previous Delta while using this test. The over 30 mutations in the spike protein in the Omicron variant do not make any difference in sensitivity using the presently available testing kits,” told Dr Harsh Mahajan, MD and founder, Chief Radiologist, Mahajan Imaging.